I had this the other day. Its the one that doesnt let you open up internet explorer or anti virus right? and if you click to buy firewall, it sends you to some program thats actually a virus.
Anyways,
Boot into safe mode, go to C:/Documents and settings/user profile/Application data <-- Have to have unhidden folders to see that one
There should be a folder called "google" and if you open it, there's 2 random named files. Delete those. Reboot. Win.
Thats what i did anyways and it has stopped ever since.
Good luck
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