HELP...Computer Gurus

Id say either it got over heated and blew something, or have the power supply checked out.

I know some Dells and HPs wont boot at all if the fan doesnt work, or if the heatsink brackets break and the heatsink is loose. I ran into a Dell not long ago that got so hot it melted the heatsink retaining brackes, and the sink came loose, and it did what you are discribing.

Consider opening the case and looking around inside.