Sometimes when you catch a virus, System Restore can present a quick fix.

To use System restore:

1. Go to the Start Menu. In Vista, type System Restore and the program should appear. Otherwise, go to Programs, Accessories, System Tools, System Restore.
2. When it has loaded, choose ‘Choose a different restore point’.
3. Select a date where the infection wasn’t present.
4. Click Next, then Finish.

Hopefully, this will remove the infection. Use an anti-virus/spyware application to clean any remaining files.