When I press the power button the fans power up and stay on until I manually turn the computer off again. They also don't change speeds like fans usually do after the first second or two.

I'm trying the unplug from power now.

I certainly never smelled anything funny. I had a feeling the computer was very hot just from running all those things at once, and fans running at full speed all the time, but I never got any figures for it, so I don't know if anything was actually at a dangerous temperature.

Thanks for the help.