Comp died, wont get past xp load screen? plz help

ok this happened about 3 months ago, i just havnt had the time to adress the problem until now (because im in shepparton with crap all to do)

my comp started to get a little unreliable, ie: random restarts, sometimes wouldnt load past boot post screen. but it usually gets there in the long run.

i went away for a week or so, come back to turn my computer on, and now everytime it gets upto the xp loading screen, it will either lock up, shut off, or display the blue screen of death. i tried reinstalling windows but that didnt seem to help at all.

the only other computer at my house is a new core2 duo, which i am not aloud to pull apart.. plus the components wont fit into mine anyway.. im using as follows (old i know!)

XP Athlon 2600+
ASUS A7N8X Deluxe
1g Corsair Value Ram
ATI X850XT
460w PSU
120g Seagate barracuda.

Can anyone suggest whats going wrong with it?

 

How often would you say that it "shuts off" and are you able to turn it back on with the power button. Honestly something like is hard to diagnose, but if the machine shuts down probably a power supply. Memory would have explained the BSOD's and the crashing, but not the shutting down.

 

You can trying putting your xp CD in and going to the repair option. Once in the repair option try running a chkdsk /p /r then after that try fixmbr and fixboot to see if those help repair windows so it will load.

 

i tried the xp repair option before, that didnt work, i also wiped my hdd and did a clean install, still didnt have an effect, the restarts would happen,.. probably a few times a week, it was over 3 months ago now so im not 100% sure on that one. i cant pull my comp apart until monday, so i will let you guys know how i go with it, thanks