E-machine ET1810-03r power problem!

I have an E?T1810 E-machine that will just power down at ay given point in time.
It will come on for a while min 30-40 and then just shutdown. (it has lasted as long as 1 1/2 hours).

I did a google and it seems as though other people have had the same problem with this model E-machine.

Some say it's a faulty PWRSupply/CPU fan. I called E-machine support and they insist there is no known problem with this model, but why have alot of others with this same model reported EXACTLY what I have in regards to this random power down scenario.

The machine has a 2.6 ghz cpu/2 gig ram an OS of Win7 home. At the time my machine shut down I was playing a game called jewel quest. I removed the game (to eliminate it as a cause) and the problem still existed. I reseated the ram checked air flow blockage/dust,removed all attached devices. Oh, and there are no multiple power dependent USB items attached whatsoever except a printer

So can anyone shed some light as to whether or not this is a power supply problem, cpu problem,ram problem or motherboard problem. I have worked on other E-machines that were known to have bad/faulty MoBo's.

Any insight would be appreciated