Thanks for replying, Chiefcrowe.
I don't know anything about that software, but you're a Senior Member, and if you say it's good, then I'll try it.
I'm a cruncher, and normally, I don't wander far from the "Distributed Computing" topic.
The machine is dual boot: Windows XP Pro (32 bit) and Windows XP64. Most of the time it runs in 32 bit mode. However there is a PrimeGrid race this month that requires a 64 bit OS, so I thought that I would run XP64 this whole month and see how it does. I thought yesterday that I might have a virus/spyware problem yesterday. After watching it for a day, I realize that I have an overheating/stability issure.
It's been running a little too hot in 32 bit mode for the last couple of months. XP64 runs for a while - then everything locks up - no keyboard/mouse action - ctrl-alt-del doesn't even work. It is necessary to power off with the switch and then boot up again. I defragged the drive -- not much help.
The thermal insulating material is generic white paste, and it's almost 4 years old - time to clean the cpu and the heatsink and reapply with ICD7.
Thanks again for your interest, and I will try that software that you recommended.