I have a Demension 2350 and my computer keeps shutting itself down. It will be running for 15 seconds or so, then turn off. The longer time lapses between me turning it on, the longer the computer will stay on. When I can get it running for a minute or so, everything seems to be working perfectly fine with the computer itself, but it will just turn off. I tried replacing the power cord, and that did not do anything. Is there some kind of power thing inside the computer that could be causing this?? Please help, and thanks!