computer shuts off by itself after a few minutes use

im running windows xp on my computer,and just last week,it started shutting off by itself while in mid-surf or typing a paper. At first it would stay on roughly 5-10 minutes, now it will stay on for about 2-3 minutes no matter how many times i try turning it back on.....is this a power supply issue or is the mother board starting to go? ........please help

 

Both power supply and motherboard are good possibilities.

Google "leaky capacitors" to see about a very common problem.

In addition, your processor overheating sounds very likely. How clean is the processor fan and heatsink? Is the processor fan even still running?

 

Heat

First thing to check is heat.
Check all the ducts in the computer are clean ( dog hair can block the flow well)
You may want to clear the dust out inside the case ( a vacuum or air compressor whatever the experts here recommend.)
Ensure that the fans are running - they may have seized. Look for a CPU fan,
(vital) , power supply fan in back and any case fans you have.
If possible there may be temperature readings in your bios ( sysem health or whatever they call it).
Lastly you may want to install additional case fans.
They are cheap.
It is most likely a heat issue.
Your motherboard is turing off your computer because of the heat to save your sysem .

 

computer shuts off

fans are still running......opened up the case and there is some dust but nothing that i would think would cause problems will vacuum out computer although and will report any progress i hope!!!!!

 

computer shuts off

guys.....thanks alot.....i vacuumed out my computer especially around and on the cpu and fan.....the computer has been running for about an hour now which it wouldnt do for the past two weeks so i think that was it......can believe something as simple as dust would cause such havoc........any ways once again thanks