PC freezes at random times

CPU: AMD X2 240
GC: 220 GT
MOBO:Asus M2N68 AM plus
RAM: 2GB 800MHZ DDR2
HD: Seagate 250GB

After few months of perfect running my PC started to freeze at random times. It can be from few min to hours. After freeze I can see last screenshot in the monitor but nothing is responding.Often computer freezes during start up even before OS is started to load and if it manages to load the OS then it would show BSOD and screen goes blank.

I ran a memory test and found errors and pc froze during the test .Then i replaced it with a new one and now the system never shows BSOD but freezes during start up(bios screen) and if it manages to load the OS successfully then there is no problem ie;PC runs without a problem UNTIL it is restartd or shutdown.
I have tried running windows scan disk and it shows no errors.
I have checked temperatures.No problem with that
Tried with different PSU's,Still freezes.
I have also noticed that after computer freeze and after I restart it – it hangs on initial start – the only thing I can see is dash on my screen.


Almost similar problem to this post

http://www.tomshardware.com/forum/ [...] ndom-times

Welcome Newcomer. Have you tried clearing CMOS yet? If not, try it. Clearing CMOS sets your BIOS back to factory defaults of the most recent revision you applied. In other words, if you've updated your BIOS, clearing CMOS will revert your BIOS back to the default settings of the update. If you didn't update your BIOS, check for one, as it may address your issue.