Caps are short for capacitors.
When it freezes again, try unplugging it and hitting the power button. Then plug it in for a few seconds, remove the power and hit the power button again.
This should charge all the caps on your mobo and in your psu and then empty them. If this 'fixes' the issue and lets you boot you probably have some bulging or blow capacitors on your mobo or in your psu.
Inspect the inside for cylinders sticking out perpendicular to the surface of the PCB. The should have small lines across them that are perforations. If they have any residue on any of them this may be your issue.
I have a two year old e-machine, running windows XP. About two months ago I had the CPU replaced, as a fan blade broke and fried the processor. It was working fine until last week, when it froze up and would not restart. Absolutely nothing would happen when turned on, exactly as it had been doing when the processor broke. The next day it worked again. Now, after a few hours, it freezes and does the same thing, only working after hours of rest. I figured the processor was overheating again somehow, even though I had a new fan put in and the whole thing cleaned out of dust, etc. I have been checking the processor temperature while it is running, and it averages between 50 and 52 degrees. Short of calling this repairman again (last time cost me $200) does anyone have any ideas?