Asus PC Probe reads the temps from the thermistor in the socket, underneath the CPU. BIOS reads the temps from the internal diode of the XP processor. BIOS is more accurate, as it's giving you the true temps of the core.
Rebooting is a sign of excess heat. Remount the HSF, using good thermal paste like Arctic Silver III. Make sure that the lip on the base of the heatsink goes over the raised portion of the CPU socket. You may have this turned around so the heatsink is not making good contact with the core.
Don't run that system until you get the heat problem figured out. You're running way too hot and risk compromising the CPU.
This space reserved for highly intelligent observations and witty remarks.
Effort & Courage are not enough without Purpose and Direction.
---- Auther Unknown