Can't open pdf attachments or downloads (Vista OS)

I have recently started using Vista (SP1) and have found that I can't open pdf files sent as Windows Mail attachments or when trying to download them from websites. With Windows Mail I get "This file does not have a program associated with it for performing this action. Create an association in the Set Associations control panel" and with Firefox I get "Acrobat plug-in - Could not launch Acrobat." I have done all of the usual things (Control Panel, Default Programs, Set Associations) and the pre-installed Adobe Acrobat Reader (version 8.1.2) is associated with pdf files. But they don't open when in the form of attachments - I first have to save them to disc and they open from there. Can you help resolve this problem? (I am OK with .doc and .ppt files)

 

Adding to my post above ... Have just found that I CAN download / open a pdf file using IE7, and from that I see that the file type is "pdf_auto_file". But my mail attachment problem remains, as does the Firefox download problem.

 

I found this on another help forum. Here it is and it worked perfectly ...
(Credit to Ramesh Srinivasan, Microsoft MVP [Windows Shell/User] http://www.winhelponline.com)

Open Registry Editor (Start, Run, type in regedit.exe, enter) and navigate to the following key:

[HKEY_CLASSES_ROOT\.PDF] (the .xxx extensions are at the top of this LONG list)

Double-click the (default) value in the right hand side window, set its data as:

"AcroExch.Document" (without quotes)

Close Regedit.exe

Restart Windows.