Hi Maffie
Some suggestions:
1. Check that you have the latest drivers for your video card
2. Same for the webcam
3. Right click the desktop then Properties->Settings->Advanced->Troubleshoot and turn down the hardware acceleration a step at a time and try again.
4. If you have a printer installed, try disabling it. It's a bit esoteric but printer drivers and graphics drivers can (rarely) conspire to trip you up..
When you swapped the driver (ks.sys), are you sure your chum had the same camera?
Cheers