random crashing?

[scottishbmxer]

for the past couple days now, my computer randomly freezes and i have to turn it off by holding the power.

i dont need to be doing anything, just moving the mouse about and it does it.

now i've already virus scanned/ad-ware scanned it and its fine.

does anyone have any ideas of how to find out the problem?

 

[sPlAtOiD]

Check RAM1st
Check Power Supply 2 nd

 

[scottishbmxer]

how do i check them?