samlewis,
sounds like to me you have a
RAM problem. Take out your
RAM and re-seat it.
If that don't work and you have more than one stick of
RAM, remove one and see if that works. If not, replace that one and pull the other. You're trying to isolate the problem stick.
I really feel though, if you just remove all your
RAM and reinstall it, your problem may go away
bigbarthy