PC Boot problems

am having an issue with when booting up, the monitor the mouse nor the Keyboard work at all. I first noticed the problem when the screensaver froze, thought “ok no biggie” rebooted (tried to anyway) than problem started. I had the XP box connected to a switch box, thinking that could be the problem, once I unplugged every thing and plugged these into the pc itself it seemed to fix the problem for about an hour after being idle than pc froze up agian. Now I am in the same boat as to where I started. Am at my witts end, about to go bald from pulling my hair out. Any suggestions would be great.