The problem started yesterday. My computer was doing perfectly fine but then it crashed while running some program. so i had to perform a hard shutdown and restart the comp. the computer was still working fine after that one time but the program was buggy and kept crashing and i had to keep doing the hard shutdown. now times this whole scenario by 30 cause i shut it down nearly that many times from all the crashes. but now my comp wont even last 5 minutes before crashing and this is with the program not even running. i uninstalled it and same thing, i get a crash after 5 minutes. and booting up takes a long time in some parts and even still it doesnt always turn on correctly, it freezes in boot up aswell. even in bios it will freeze. so now im stuck. i tried to reinstall vista and it froze in the middle of reinstallation and then i ran the thing again and finished it up but its still crashing. so im guessing the motherboard got ruined because if it was power supply it would shut down after the crash wouldnt it? and its probably not software cause i completely reset the comp and reinstalled vista and i even tried switching wireless cards and mouse/keyboard. i also ran hp diagnostics tools and it says harddrive memory and cpu passed all the tests.
so pleeeaaase help meee. i cant use this thing without it freezing up every 5 minutes. i actually havnt even been able to get past the initial time setup pages and stuff when you reinstall vista. (using a dif. comp)

I have a Dell Lattitude 620 with 2 GB RAM, Windows XP SP2. I find that it hangs / freezes during use all of a sudden. mouse, keyboard nothing works. I have no choice to boot it again.

I have tried to look at the Event Log Applications, System, etc. Do not find any entry that would help me identify the problem.

Would like to know how best I can go about identifying the problem. Is it some software? Is it hardware issue?

I had done a diagnostic boot some time back and found DST error and replaced the hard-disc. Defragged it too. This too has not solved the problem.

Will appreciate ideas from you.