Run a scan while in safe mode. To enter safe mode you need to tap F8 while the computer starts up. If the windows logo appears before you get a menu you've missed it. When the list pops up, select 'safe mode with networking' so you can receive update for the antivirus software if you have an internet connection.
Safe mode usually stops viruses from loading/starting up. In normal mode they start up as normal and have the ability to lock files etc that would prevent you from removing them.