Windows XP, P-III, Restart Problem

My PC usually restart without no any reason according to my knowledge. I have Windows XP, P-III. Please suggest me the solution....

try system restore i think you had install something that automatically restart your pc

Disable automatic restart from system options to find out the problem.

Check CPU Fan if it is working.

Automatic restarts usually occur due to PSU/fans etc.

Thanks for reply, i will try the suggestions