My desktop PC has a PENTIUM 4 and 4MB of RAM, runs XP Pro.  It had been running fine and then overnight the computer locked up on the screen SAVER.  I rebooted it with the power switch.  It was ok.  then during the day a few times it locked up again, unresponsive to anything other than the power switch shut down.  In the late afternoon, after a reboot it didn't load Windows all the way and froze up again.  I did try restarting in SAFE mode which locked up.  It did reboot and load Windows a time after that but will only run for about 30-sec to a min before it locks up now.

I have done simple things like upgrade memory and LEARN software quickly but I am not an expert with hardware.  Anyone have any ideas about what it could be or how to start troubleshooting the problem.  Think it is hardware or software problem?

Thank you for your help!How old is your computer? Try to clean first the inside of your CPU and see if the problem persists.4MB of ram? I suppose you mean gb?  But even so... a p4 with 4gb of ram?  Anyway... try doing a repair install or reinstalling windows