I have a Emachine about 4 yrs. old, the only upgade was to add more ram. Sometimes it would just shut down. The monitor will just go black but the power indicator on the computer is still on and I can still hear the computer running. I tried pressing the caps lock to see if the indicator light comes on on the keyboard and it doesn't so that tells me that it's not the monitor. I would have to turn the power off and back on to boot up. Sometimes it will shut down after a few minutes after the reboot. Most of the times it will be alright for weeks at a time. What could be the problem?