HP pavilion 503n Shutdown problems after boot

[muckmail]

I have an hp pavilion 503n computer with a 1.7meghertz celerion processor. 2, 3 or maybe 4 mins. after boot the HP will reboot. When I first boot it goes shows a hp recovery loading bar on the
bottem of the screen before it reboots. If I go into the
setup the machine will also reboot after a few mins.
The machine has XP home ed. on it.
Any suggestions on trouble shooting this machine?
thank you,
muckmail

 

[FlashDude]

Check your temps with a program like speedfan, And have you defraged your hdd lately and ran adware/spyware/virus removal programs?

 

[muckmail]

What tempatire program do you recommend? I used a fixed drive that does not have any virus on it. I cleaned the heatsink to the processor fan. I add more heat sink lube inbetween the processor
& heat sink. Any suggestions form this point?
thank you,