Quote - Have you switched off 'indexing' on the hard drives?
This is always one of the first things that I do.

The other thing could be a peculiar install of an AntiVirus program.
What AntiVirus have you got installed?

What exactly is "indexing"?  If it's something important that is needed for my restore point, then I don't think I want to turn that off.

I'll try reinstalling my antivirus program and see if that helps.  I use e-Trust Antivirus and have done so for years. I used the free beta version of it when it was called something else. I really like it and it hasn't let me down in all of the time I've been using it.

Quote - Do you happen to have the PC plugged in to a  UPS (uninteruptable power supply)?  I had a bad connection on the communication cable between it and PC, which was shutting my PC down.  The software would see the connection disappear and think I was on battery power and then shut my PC off.

Actually, I think I am. I have my computer connected to an APC power bar that has battery backup and I have it plugged into the power surge/battery backup area instead of just the power surge. I'll plug it into my other power surge bar and see if that helps.

Quote - We had this problem also and it turned out to be the power supply.  Some sort of protection, when it was failing so you did not hurt your hard drive, it would reboot, but it was a bad power supply.  Sharen

I'm thinking that's all it is too. I'm not getting any blue screens of death since having turned off auto restart, and it only seems to happen when I'm doing something intensive like copying large batches of files from CDs to my hard drive, or searching the hard drive (that's all I've done so far).  For the past couple of hours I've just been moving around small amounts of files between drives and the computer hasn't shut itself down while I've been doing those little tasks.

I'll  if these ideas don't fix it, then I'll call them tomorrow about it. I don't mind paying additional to have a better power supply put in if that's the case, but if they try charging me labour in order to change out the power supply I'll kick up a fuss because I specifically asked for a large enough power supply to run my system and if it's shutting down because of an inadequate power supply, then that's not "adequate". I will pay the difference between the cost of this one and a better one though.

Anyway, I'll see what they say.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi