Here is a list of indicators (from Microsoft) that your computer might be infected by a virus:
- Your computer runs more slowly than normal
- Your computer stops responding or locks up often
- Your computer crashes and restarts every few minutes
- Your computer restarts on its own and then fails to run normally
- Applications on your computer don't work correctly
- Disks or disk drives are inaccessible
- You can't print correctly
- You see unusual error messages
- You see distorted menus and dialog boxes