WinXP SP2

CPU – Celeron 2.4ghz, P4x266 nfsx MB, 1.0GB RAM, 160GB hd, Geforce 6200, WINXP w/ SP2

Whenever i encode or coverting video, the PC just hang without blue screen..This OS just formatted.

HAve check , whenever CPU usage 100%, it will hang any time, please advise.
IS there any software to control all this thing?