It's weird, this computer keeps turning off without warning, sometimes while windows is loading up, sometimes after it's already loaded up. If we leave it off for a day, we can run it for an hour, and then it'll turn off, and turn off after a minute if we try to turn it back on. Help?

Thermal overload cutout? Pentium chips come with inbuilt thermal protection. Boot into bios and look in the system health section. What temperature is the CPU reporting? I used to have a signature but it disappeared and I just couldn't be bothered writing another so please feel free to ingore this.

I'd go along with Richard's suggestion - sounds like thermal cut-out. (hopefully not a failing controller ;) 1. Check the fan and ventilation of the computer isn't clogged up with dog hair. 2. If you've not heat-sunk the internal fan with thermal paste, then it might be worthwhile doing.

I don't think the fan is clogged up... it's whirring away at 2721 RPM, and there's no dogs around. The temperature of the CPU (from the bios) is a mild 27 degrees when it shuts off. This is weird...