I am assuming that the basic hardware troubleshooting has not been dealt with.
Ok here we go.
1. Please check if your CPU internals are free from dust bunnies and the like. A can of air will really help.
2. Boot at safe mode. Since you posted on Windows XP, restart your computer, before you see the windows logo hit F8 on your keyboard and boot at safe mode.
3. On safe mode, check if the computer is not freezing.
If yes, its either that you have OS issues or hardware issue.
If no, its most likely that once of your start up items is / are causing this problem. Perhaps an expired AV.
Do this : http://www.howtogeek.com/howto/windows/qui...ows-xp-startup/
4. Boot regularly and check if the problem persist.
Please post your results.
Hardware tech when I was in college.
1st job was a network support for SOHO
2nd job was lappy tech
3rd Job way out of my league but its nice...