Reboot in safe mode.
Go to your Local Drive.
Go to Documents and Settings (and choose You).
Go to Local Settings. (If this doesn't appear, go to tools/folder options/view/and click the tab beside "Hidden files and folders" and Apply)
Go to to Application Data
Look there for a nonsense folder that begins with the letter a (forget the string).
It's abeghfdgt or something ridiculous like that.
Inside that folder will be a program called osadware.exe (again, don't remember the exact file name) or something of that nature and it will say it is a Microsoft Corporation file. It is not.
Delete it and it's containing folder.
Empty your recycle bin.
Reboot into your normal mode.
Then be careful where you are getting your torrents.