It could also be the W32/Crog.worm.
If the bropia worm removal tool doesn't remove it try this one, sounds like it to me:
http://securityresponse.symantec.com/avcenter/FixSflog.exe
I think it closes you browser when you go to anything related to antivirus' etc. so if the link above doesn't work, try this mirror:
http://www.virushelp.nl/download/fixsflog.exe
See this
thread for more information