I disabled unnecessary extensions, and now I can't even get to the finder...

The CPU could be overheating. That is what was causing my Beige G3 to crash in between one and seven days for a year or two.
If you have it overclocked, move the jumpers back to the proper setting for your CPU module.

In any case, pull the heat sink, clean off the old heat sink compound (likely to be a useless powder by now) and reapply new heat sink compound.

Click to expand...

I never thought of that. The processor is not overclocked, to the best of my knowledge. Maybe I should install another fan or something? I'll blow the thing out with compressed air and check the processor.

By the way, I have Farallon Timbuktu installed on the server, to make it headless. I wonder if there's a problem with it?