I solved the problem in my case.
I had both computer freezing and 'machine check' log msg.
I tried to find the cause by any kinds of methods.
Finaly, I pluged off the power from M/B. Then i suprised that power 2 plastic pins connecting to M/B had been burend among total 20pins.
I guess irregular power was the cause. and I have experienced no freezing and no log msg after replacing burned power to another power.
If freezing and log msg occur, i will reply here again.
Good Luck to all