Hi Smurfjet,
Are you running windows 98?
If so I believe that if you can boot to a dos prompt you should be able to fix this by opening win.ini in a text editor. I think that :
edit c:/windows/system/win.ini
should get you going.
If I rember correctly your should be able to find the right beits to edit pretty easily. Might be worth saving a copy before tinkering.
Can anyone confirm my memory here - it's been a while!
Memetic.