Hi, Yes, you can run Scandisk in DOS or in Safe Mode.
DOS: Select Shutdown.....Restart in DOS mode.....at the C:\Windows prompt, type: scandisk and hit Enter key.
You can run the Thorough surface scan, but it takes a few hours....
There may be some running background processes that have to be turned off for scandisk to run....usually, Safe Mode will handle these for you.
SAFE MODE: At bootup, press and hold the CTRL key, should see the menu item, "Safe Mode".....select that. At the desktop, your video will look greyed out....because a lot of drivers are not running......this is normal. Run Scandisk the same way from the Programs>Accessories>SysTools menu.
Shut down screensaver before running scandisk....
May help to temporarily turn off antivirus program, too, but you have go back and reenable it afterward.
By the way, defrag will run from Safe Mode, too.