I've solved my problem but the solution makes no sense to me. Therefore, I'll ask this question to see if anyone can help me understand.
Custom built PC
Win XP Home SP3 (with all updates)
28" Hanns-G monitor
Graphics board connected using a 6' DVI to HDMI cable
-For some time, there were artifacts on the pre-boot screen (i.e. prior to the Windows Logo). After booting to Windows all seemed to work well.
-Recently, after about 30 minutes using the computer, the screen would either display a series of solid colours, then go black, sometimes the computer would freeze or reboot on it's own.
- I re-seated the graphics board and ensured that connections were secure
- I installed CPU & GPU heat monitors (no problems found)
- I suspected the graphics board, so I swapped out the entire PC for an older model that was no longer in use. Surprisingly, I still had the same problem.
- Then, I replaced the DVI to HDMI cable with a standard HDMI cable and that solved the problem!
I had always assumed that the cable between the graphics board and the monitor was one way - Graphics board to monitor. (i.e. The computer will boot and run without a monitor connected). I can see how a defective video cable could cause display problems. However, I can't see how a defective video cable could possibly cause the computer to freeze or reboot.
Can anyone enlighten this poor soul?