Try to do full scan with following website:
XP:
http://onecare.live.com/site/en-us/default.htmVista/Win 7:
http://onecare.live.com/site/en-us/center/whatsnew.htmDo full scan and browse using internet explorer 8, if website has been blocked then try to do scan using safemode with networking
restart your PC, press F8 continusly before Windows logo come up and then chose:
safemode with networking (use arrow key and press enter)
Then try to run full scan by this website