Windows Defender has found a "SettingsModifier", don't know how to proceed

Today, Windows Defender uploaded the latest definition file, and now it tells me that I've got a Medium risk called:
SettingsModifier: Win32/PossibleHostsFileHijack. Alert level: Medium
file: C:\Windows\system32\drivers\etc\hosts

I don't know whether this is a false positive and whether I should quarantine, ignore or clean it.
I clicked on the link Windows Defender supplied:
http://www.microsoft.com/security/p...eHostsFileHijack&threatid=1758608427027806866

I've also included a HijackThis scan below:

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 15:43:26, on 09.03.2009
Platform: Windows Vista SP1 (WinNT 6.00.1905)
MSIE: Internet Explorer v7.00 (7.00.6001.18000)
Boot mode: Normal

Running processes:
C:\Windows\SYSTEM32\WISPTIS.EXE
C:\Program Files\Common Files\microsoft shared\ink\TabTip.exe
C:\Windows\system32\Dwm.exe
C:\Windows\Explorer.EXE
C:\Windows\system32\taskeng.exe
C:\Program Files\Windows Defender\MSASCui.exe
C:\Program Files\Apoint\Apoint.exe
C:\Program Files\Sony\ISB Utility\ISBMgr.exe
C:\Program Files\Common Files\Symantec Shared\ccApp.exe
C:\Windows\System32\rundll32.exe
C:\Program Files\HP\HP Software Update\hpwuSchd2.exe
C:\Windows\ehome\ehtray.exe
C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
C:\Program Files\Windows Media Player\wmpnscfg.exe
C:\Windows\system32\taskeng.exe
C:\Program Files\WIDCOMM\Bluetooth Software\BTTray.exe
C:\Program Files\Sony\VAIO Update 4\VAIOUpdt.exe
C:\Windows\ehome\ehmsas.exe
C:\Windows\system32\WTablet\Pen_TabletUser.exe
C:\Program Files\Apoint\ApMsgFwd.exe
C:\Windows\System32\rundll32.exe
C:\Program Files\Apoint\Apntex.exe
C:\Windows\System32\mobsync.exe
C:\Program Files\Common Files\Microsoft Shared\Ink\InputPersonalization.exe
C:\Program Files\Internet Explorer\IEUser.exe
C:\Windows\system32\SearchFilterHost.exe
C:\Program Files\Trend Micro\HijackThis\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.symantec.com/home_homeof...upgrade2007/vista/select_product.jsp?site=nuc
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://vaio-online.sony.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://go.microsoft.com/fwlink/?LinkId=69157
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant =
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
O1 - Hosts: ::1 localhost
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - C:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: (no name) - {1E8A6170-7264-4D0F-BEAE-D42A53123C75} - C:\Program Files\Common Files\Symantec Shared\coShared\Browser\1.5\NppBho.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - C:\Program Files\Google\Google Toolbar\GoogleToolbar.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files\Google\GoogleToolbarNotifier\5.0.926.3450\swg.dll
O2 - BHO: Google Dictionary Compression sdch - {C84D72FE-E17D-4195-BB24-76C02E2E7C4E} - C:\Program Files\Google\Google Toolbar\Component\fastsearch_219B3E1547538286.dll
O3 - Toolbar: Show Norton Toolbar - {90222687-F593-4738-B738-FBEE9C7B26DF} - C:\Program Files\Common Files\Symantec Shared\coShared\Browser\1.5\UIBHO.dll
O3 - Toolbar: &Google Toolbar - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - C:\Program Files\Google\Google Toolbar\GoogleToolbar.dll
O4 - HKLM\..\Run: [Windows Defender] %ProgramFiles%\Windows Defender\MSASCui.exe -hide
O4 - HKLM\..\Run: [Apoint] C:\Program Files\Apoint\Apoint.exe
O4 - HKLM\..\Run: [ISBMgr.exe] "C:\Program Files\Sony\ISB Utility\ISBMgr.exe"
O4 - HKLM\..\Run: [E-Flyer] "C:\Program Files\Sony\E-Flyer\SubFlyer.exe"
O4 - HKLM\..\Run: [ccApp] "C:\Program Files\Common Files\Symantec Shared\ccApp.exe"
O4 - HKLM\..\Run: [Symantec PIF AlertEng] "C:\Program Files\Common Files\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\PIFSvc.exe" /a /m "C:\Program Files\Common Files\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\AlertEng.dll"
O4 - HKLM\..\Run: [Adobe Reader Speed Launcher] "C:\Program Files\Adobe\Reader 9.0\Reader\Reader_sl.exe"
O4 - HKLM\..\Run: [NvSvc] RUNDLL32.EXE C:\Windows\system32\nvsvc.dll,nvsvcStart
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\Windows\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\Windows\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [HP Software Update] C:\Program Files\HP\HP Software Update\HPWuSchd2.exe
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\QTTask.exe" -atboottime
O4 - HKCU\..\Run: [ehTray.exe] C:\Windows\ehome\ehTray.exe
O4 - HKCU\..\Run: [swg] C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
O4 - HKCU\..\Run: [WMPNSCFG] C:\Program Files\Windows Media Player\WMPNSCFG.exe
O4 - HKCU\..\RunOnce: [FlashPlayerUpdate] C:\Windows\system32\Macromed\Flash\FlashUtil9f.exe
O4 - HKUS\S-1-5-19\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /detectMem (User 'LOCAL SERVICE')
O4 - HKUS\S-1-5-19\..\Run: [WindowsWelcomeCenter] rundll32.exe oobefldr.dll,ShowWelcomeCenter (User 'LOCAL SERVICE')
O4 - HKUS\S-1-5-20\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /detectMem (User 'NETWORK SERVICE')
O4 - HKUS\S-1-5-18\..\Run: [Picasa Media Detector] C:\Program Files\Picasa2\PicasaMediaDetector.exe (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [Picasa Media Detector] C:\Program Files\Picasa2\PicasaMediaDetector.exe (User 'Default user')
O4 - .DEFAULT User Startup: Audio Filter.lnk = C:\Program Files\Sony\SonicStage Mastering Studio\Audio Filter\SSMSFilter.exe (User 'Default user')
O4 - Startup: OneNote 2007 Bildschirmausschnitt- und Startprogramm.lnk = C:\Program Files\Microsoft Office\Office12\ONENOTEM.EXE
O4 - Global Startup: Bluetooth.lnk = ?
O4 - Global Startup: HP Digital Imaging Monitor.lnk = C:\Program Files\HP\Digital Imaging\bin\hpqtra08.exe
O4 - Global Startup: VPN Client.lnk = ?
O8 - Extra context menu item: E&xport to Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office12\EXCEL.EXE/3000
O8 - Extra context menu item: Send image to &Bluetooth Device... - C:\Program Files\WIDCOMM\Bluetooth Software\btsendto_ie_ctx.htm
O8 - Extra context menu item: Send page to &Bluetooth Device... - C:\Program Files\WIDCOMM\Bluetooth Software\btsendto_ie.htm
O9 - Extra button: An OneNote senden - {2670000A-7350-4f3c-8081-5663EE0C6C49} - C:\PROGRA~1\MICROS~2\Office12\ONBttnIE.dll
O9 - Extra 'Tools' menuitem: An OneNote s&enden - {2670000A-7350-4f3c-8081-5663EE0C6C49} - C:\PROGRA~1\MICROS~2\Office12\ONBttnIE.dll
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\Office12\REFIEBAR.DLL
O9 - Extra button: @btrez.dll,-4015 - {CCA281CA-C863-46ef-9331-5C8D4460577F} - C:\Program Files\WIDCOMM\Bluetooth Software\btsendto_ie.htm
O9 - Extra 'Tools' menuitem: @btrez.dll,-12650 - {CCA281CA-C863-46ef-9331-5C8D4460577F} - C:\Program Files\WIDCOMM\Bluetooth Software\btsendto_ie.htm
O13 - Gopher Prefix:
O16 - DPF: {644E432F-49D3-41A1-8DD5-E099162EEEC5} (Symantec RuFSI Utility Class) - http://security.symantec.com/sscv6/SharedContent/common/bin/cabsa.cab
O23 - Service: Adobe Active File Monitor V5 (AdobeActiveFileMonitor5.0) - Unknown owner - C:\Program Files\Adobe\Photoshop Elements 5.0\PhotoshopElementsFileAgent.exe
O23 - Service: Automatic LiveUpdate Scheduler - Symantec Corporation - C:\Program Files\Symantec\LiveUpdate\ALUSchedulerSvc.exe
O23 - Service: Symantec Event Manager (ccEvtMgr) - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\ccSvcHst.exe
O23 - Service: Symantec Settings Manager (ccSetMgr) - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\ccSvcHst.exe
O23 - Service: Symantec Lic NetConnect service (CLTNetCnService) - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\ccSvcHst.exe
O23 - Service: COM Host (comHost) - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\VAScanner\comHost.exe
O23 - Service: Cisco Systems, Inc. VPN Service (CVPND) - Cisco Systems, Inc. - C:\Program Files\Uni Basel\VPN Service\cvpnd.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: Image Converter SCSI Service (ICScsiSV) - Sony Corporation - C:\Program Files\Sony\Image Converter 3\ICScsiSV.exe
O23 - Service: IcVzMonLauncher - Sony Corporation - C:\Program Files\Sony\Image Converter 3\IcVzMonLauncher.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files\Common Files\InstallShield\Driver\1150\Intel 32\IDriverT.exe
O23 - Service: Image Converter video recording monitor for VAIO Entertainment - Sony Corporation - C:\Program Files\Sony\Image Converter 3\IcVzMon.exe
O23 - Service: Symantec IS Password Validation (ISPwdSvc) - Symantec Corporation - C:\Program Files\Norton Internet Security\isPwdSvc.exe
O23 - Service: IviRegMgr - InterVideo - C:\Program Files\Common Files\InterVideo\RegMgr\iviRegMgr.exe
O23 - Service: LiveUpdate - Symantec Corporation - C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
O23 - Service: LiveUpdate Notice Service Ex (LiveUpdate Notice Ex) - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\ccSvcHst.exe
O23 - Service: LiveUpdate Notice Service - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\PIF\{B8E1DD85-8582-4c61-B58F-2F227FCA9A08}\PIFSvc.exe
O23 - Service: MSCSPTISRV - Sony Corporation - C:\Program Files\Common Files\Sony Shared\AVLib\MSCSPTISRV.exe
O23 - Service: PACSPTISVR - Unknown owner - C:\Program Files\Common Files\Sony Shared\AVLib\PACSPTISVR.exe
O23 - Service: Sony SPTI Service (SPTISRV) - Sony Corporation - C:\Program Files\Common Files\Sony Shared\AVLib\SPTISRV.exe
O23 - Service: SigmaTel Audio Service (STacSV) - IDT, Inc. - C:\Windows\system32\stacsv.exe
O23 - Service: Symantec Core LC - Unknown owner - C:\Program Files\Common Files\Symantec Shared\CCPD-LC\symlcsvc.exe
O23 - Service: Symantec RemoteAssist - Symantec, Inc. - C:\Program Files\Common Files\Symantec Shared\Support Controls\ssrc.exe
O23 - Service: Symantec AppCore Service (SymAppCore) - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\AppCore\AppSvc32.exe
O23 - Service: TabletServicePen - Wacom Technology, Corp. - C:\Windows\system32\Pen_Tablet.exe
O23 - Service: VAIO Entertainment TV Device Arbitration Service - Sony Corporation - C:\Program Files\Common Files\Sony Shared\VAIO Entertainment Platform\VzCs\VzHardwareResourceManager\VzHardwareResourceManager.exe
O23 - Service: VAIO Event Service - Sony Corporation - C:\Program Files\Sony\VAIO Event Service\VESMgr.exe
O23 - Service: VAIO Media Integrated Server (VAIOMediaPlatform-IntegratedServer-AppServer) - Sony Corporation - C:\Program Files\Sony\VAIO Media Integrated Server\VMISrv.exe
O23 - Service: VAIO Media Integrated Server (HTTP) (VAIOMediaPlatform-IntegratedServer-HTTP) - Sony Corporation - C:\Program Files\Sony\VAIO Media Integrated Server\Platform\SV_Httpd.exe
O23 - Service: VAIO Media Integrated Server (UPnP) (VAIOMediaPlatform-IntegratedServer-UPnP) - Sony Corporation - C:\Program Files\Sony\VAIO Media Integrated Server\Platform\UPnPFramework.exe
O23 - Service: VAIO Media Gateway Server (VAIOMediaPlatform-Mobile-Gateway) - Sony Corporation - C:\Program Files\Sony\VAIO Media Integrated Server\Platform\VmGateway.exe
O23 - Service: VAIO Media Content Collection (VAIOMediaPlatform-UCLS-AppServer) - Sony Corporation - C:\Program Files\Sony\VAIO Media Integrated Server\UCLS.exe
O23 - Service: VAIO Media Content Collection (HTTP) (VAIOMediaPlatform-UCLS-HTTP) - Sony Corporation - C:\Program Files\Sony\VAIO Media Integrated Server\Platform\SV_Httpd.exe
O23 - Service: VAIO Media Content Collection (UPnP) (VAIOMediaPlatform-UCLS-UPnP) - Sony Corporation - C:\Program Files\Sony\VAIO Media Integrated Server\Platform\UPnPFramework.exe
O23 - Service: VAIO Content Metadata Intelligent Analyzing Manager (VcmIAlzMgr) - Sony Corporation - C:\Program Files\Sony\VCM Intelligent Analyzing Manager\VcmIAlzMgr.exe
O23 - Service: VAIO Content Metadata XML Interface (VcmXmlIfHelper) - Sony Corporation - C:\Program Files\Common Files\Sony Shared\VcmXml\VcmXmlIfHelper.exe
O23 - Service: VAIO Entertainment UPnP Client Adapter (Vcsw) - Sony Corporation - C:\Program Files\Common Files\Sony Shared\VAIO Entertainment Platform\VCSW\VCSW.exe
O23 - Service: VAIO Entertainment Database Service (VzCdbSvc) - Sony Corporation - C:\Program Files\Common Files\Sony Shared\VAIO Entertainment Platform\VzCdb\VzCdbSvc.exe
O23 - Service: VAIO Entertainment File Import Service (VzFw) - Sony Corporation - C:\Program Files\Common Files\Sony Shared\VAIO Entertainment Platform\VzCdb\VzFw.exe
O23 - Service: XAudioService - Conexant Systems, Inc. - C:\Windows\system32\DRIVERS\xaudio.exe

--
End of file - 12983 bytes

Have also run a Quick Scan by Norton Internet Security 2007, it didn't find anything.
I will run a full scan.
I have not noticed any abnormal behaviour on my computer and I can access security sites normally etc.
Can anyone tell me what's going on? Thanks in advance
Update: NIS complete scan has finished - it didn't find anything.

 

I got into contact with a Symantec expert (Michael York): he told me to test my computer for malware with Norton's online scanner. It didn't find anything. Nada. Nothing. I am really at a loss about what is going on here. I am still wondering whether Windows Defender has detected a false positive or not. I can only say that I am confused. And tired.

 

Problem solved. I went to chat with a Microsoft expert, Jem, and s/he accessed my computer via remote connection, stated that there was a baddie in the hosts file, and re-created the hosts file. After that, the computer was rebooted, Windows Defender run again...and the scan came up clean. Jem sent me the summary of the action taken in an e-mail, here it is:
---

Problem Description:
Browser Hijacker

Troubleshooting Performed:

Action: Check host file
Result: Delete the old host file then created a new host file

Action: On Windows Defender
Result: Clicked remove all infections

Action: Restart computer, run Windows Defender
---
Details about the baddie:

Win32/PossibleHostsFileHijack

It seems to like to reside in:
C:\Windows\system32\drivers\etc\hosts

Windows Defender considers it a "settings modifier". Risk: Medium.
I'm going to inform Symantec of this. Nightie night *faints*.

 

UPDATE: The Windows Defender WAS a false positive after all! People are complaining about it, and Windows Defender has corrected this problem with a fresh definition file. Nice to know I was right.