My computer keeps rebooting

We just moved apartments last weekend, and our computer was fine before we packed it all up and moved it. Now we have it all set up again, and when we push the on button, it brings up the main "Compaq" opening screen, then it reboots itself. Sometimes it can get to the desktop, and but then it still reboots. I can't seem to fiqure out the problem, because everything was fine a week ago.

I can't even run a virus scan because it doesn't usually stay on long enough to reach the desktop. I even opened it up and made sure everything on the inside was connected and not loose. And the fans were working, so it's not overheating.

Can anyone tell me if there is something I should be looking for on the inside, as I didn't really know what I was looking for. Please help!
continually reboots, except in safe mode