Posted 04 September 2009 - 05:19 AM
I guess you have tried all the obvious things - but just in case, here goes:
Change the VGA cable with a new one - fault inside the wire
Check inside the PC tower that nothing is loose - e.g soldering, wiring etc
Revert back to the old BIOS perhaps?
Check on the screen that nothing is loose inside - same again, soldering, wiring...
Check the drivers for your display program etc. I had a similar problem - updated ATI Catalyst Control - eliminated the problem
Have you managed to get it checked on your friends monitor yet?