What is the sympton of Instability and Crashing system?
 

And what cause it to become instability and crashing?

symptoms: programs/windows crashing ?
causes: bad cpu, bad memory, bad mobo, bad psu, bad hdd, bad vga, bad drivers, virus, bad cooling, bad windows, ...

while i play F.E.A.R with One 500W generic PSU and my computer suddenly restart but when i use 2 PSU and play F.E.A.R my computer did not restart but it crash to windows and appears a new window that show you want to send error report or dont sent what the problem is that i have 512MB 166Mhz plz help me.

yellow ... plz use points, comma's etc ... This is hard to read man.
Try running [g]memtest86+[/g] (<- google) .
We can't help you if you don't give enough specs of your computer setup (like what is connected to PSU1 and what to PSU2)

PSU1 500Watt connected to motherboard and cpu.
PSU2 connected to cdrom,hdd and many fan.

sempron 2200 and a GF 6200, can run that with a 300W ~ 400W psu with no prob.

Mybe my 512ram is a problem??

You have anything overclocked?

P.S. test you ram using memtest!

okay

Uhm...okay??? Lol :^D You mean't the ram test right? (I would assume). But you still haven't answered if you're overclocked or not. ;)