I have new memory in the system. I have replaced the thermal paste on the CPU. I have reinstalled Windows. I have updated the BIOS for the Shuttle motherboard.

I'm still having problems getting the thing to boot reliably.

Now at least I have zero problem loading Windows onto the machine, but I can't give this machine to its future owner and say "don't worry, just turn it on and off until it starts up, then you're good to go. Just try not to turn it off and you'll be fine!"

Any more ideas guys? I really appreciate the help so far. It was killing me all weekend because I ordered the new memory for overnight mail on Thursday, but I guess it was a little too late in the day so it got here Monday. Then I pop in the RAM and find it didn't solve the problem (though I think that was another problem that needed fixing anyway).