A very special thankyou to all those who added suggestions and comments for my PC troubles yesterday – your advice was all fantastic and very much appreciated. After 24 hours of continuous running I think my problems may have been sourced from poorly connected devices after all. My CDRW cable was very slightly disengaged when I had another good look at it, and the memory dimm – though it didn’t appear to move when I jiggled it – hasn’t caused any problems since.
I’m still going to look in to better cooling for this machine. At the moment the single fan on the CPU and the fan in the power supply I don’t see as sufficient for the conditions in Brisbane. Probably won’t go the liquid cooling track, regardless of how fabulous I think that is, but even an extra little 12cm fan may improve temperature a bit.