Hugh, I'm thinking power supply too. My home PC died a little while back due to a bad power supply. The bummer was that it took out the mother board when it died. My puter was 6 and a half years old. All backed up but lost a whole bunch of programs that I used.
If you need a power supply, I have a brand new one I'll send your way if you want it. Maybe you will be luckier then I.