I have a problem with the computer failing to SEND a signal to the monitor and keyboard. This usually occurs after several hours of use. I can be in the middle of a game or working on college papers and my monitor will go blank and I get a message that says "no signal." When this happens my keyboard also stops functioning. When this happens, I have to manually shut down the computer; afterwards, it takes several hours before the computer will send a signal to the monitor and keyboard again. Usually on restart, the power does come on. I can hear the hard drive start up, the fans run, and everythng seems ok except the lack of signal. Then again, SOMETIMES it starts up with no problem. I have taken it to two different technicians who can find nothing wrong.

Can anybody give me any good advice or suggestions.It sounds to me as if you have a heat issue...
Remove a side PANEL and place a small desk size fan blowing air into the machine...if the symptoms go AWAY that machine needs more cooling.
Check to see all fans operate properly
Move the machine if it's in a CLOSED area.
Consider adding another case fan.