No i doubt it could be a virus. Has it ahppened recently?
Try using System Restore and go back to a previous state (Windows 2000,ME, xp) Go to start, accessories, System Tools, System Restore. Go back to when it occured if you can. Don't worry, it won't delete any documents, but mght loose programs you've installed in that time.
They might start working again after it does its task and restarts
Hope this helps