Computer randomly shutting downFollow

I have an EMachines computer, and for any of you familiar with one, on the tower there is an E button that has a green ring around it that you can push. Lately my computer has just been turning itself off, where the orange light bellow the E is still orange but the ring around the E has no light. The monitor is still workign also.

Is it actually shutting off or just going into sleep mode? If there are lights on the tower on, then the machine is still on.

Right-click on the desktop (anywhere not occupied by an icon) and choose "Properties".

Click on the "Screen Saver" tab

Click on "Power"

System Standby, Turn off Hard Disk, and System Hibernates should be set to "Never", unless you want them to do their thing. If any of these are set to a time, that is most likely the problem.

I'd says that this is an accurate assessment of the problem. That orange light is your hard drive activity indicator, and from what you've described, the computer is definitely still running when this happens.