Risk History log any help?? Just installed all new updates for ie8 and ff5.
Action
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Risk Type
What AV product and Version are you running?
Try disabling System Restore. Make sure you have the latest Certified or Rapid Release definitions, and then running a ful scan in Safe-mode.
http://www.symantec.com/business/theme.jsp?themeid=full-system-scan
If that fails to do the trick, try the PE removal tool.
Removal Tool