presario 1500 powering off

Hi, I'm having a problem with my Compaq Presario 1500 powering off
when I do certain things. It happens SOMETIMES when I move the
monitor, and SOMETIMES when I plug/unplug devices into the USB port.
I've updated the BIOS with no success. I emailed Compaq support and
they told me it was probably a hardware problem (which is what I
figured). I've done a lot of desktop repair but I have never repaired
a laptop before. I'd much rather do it myself than take it somewhere.
I'm looking for as much advice as possible. If anyone has solved this
problem before please tell me how.. or if anyone just has suggestions
for troubleshooting or where to get information on repairing laptops I
would appreciate it. Thank you!

Steve Weatherly