As its happening when you are adding extra load to the power supply, I would suggest getting hold of HWMonitor (
http://www.cpuid.com/hwmonitor.php) or similar. So you can look at how stable the voltages are coming out of the PSU. I think it's the 12V and 5V values you need to look at for CD-rom and HDD drives
Plus to me your CPU temp looks high @ 54°C, shouldn't it be running @ around 40ish. Also the above will monitor temperatures
CPU specs:
http://www.cpu-world.com/CPUs/K8/AMD...000CZBOX).html (Max temp. 55 - 63°C)
If you leave the HW Monitor running it will log Min / Max values and if your PC freezes you should be able to see what values you're getting, as long as you don't have a screensaver that is.