computer keeps shutting off

I'm running:
XP Pro SP2
80G HD (40G free)
Radeon 9200
AMD Sempron 2600 1.83GHz
1G of Ram

Went into device manager ... no problems
In fact I was in device manager and blink ... computer shut off
Something weird though ... Red light is on when computer is on ....
when something is going on, green light will be on ...
When computer shuts down, all I hear is a noise as if I had shut it down normally ....
After the computer goes off, the green light is on, but no red, and no noise, and screen is black.

I have done nothing different lately to cause this .... anything I could check to see what is going on.

Oh yes, this computer is not on the internet.

Please, I need suggestions .... thank you

 

I think it is heat related, check your cpu heatsink and be sure its not full of lint, dirt. Be sure the fan is running on the heatsink, and last but not least, the heatsink grease could be old and woreout, I have seen some grease set up like concrete and be useless. ed

 

Thanks for helping me again .....

You are referring to the fan on the power supply ??? I'm not sure what a heatsink is.

 

No, if you pull the side cover off you will see an aluminum heatsink[ kinda square with fins, and a fan on top] sitting on the motherboard, see if it is dirty inside the case. ed

 

I think I can handle that ... first thing in the morning ... right now I think I am off to sleepy land.

Thank you and I will let you know if that helped.

 

Well, tunered you did not warn me about what might happen when I opened my computer to clean it .... the dust bunnies attacked me severally. It was really bad, but I got it cleaned, all parts are moving, but something is still wrong.

Got the computer back in the house, hooked everything up ... turned it on ... and in about five minutes or actually less than that ... it shut down.

Is this where I get out the shotgun and blow the computer up ?????

I sure do need more ideas now that I have a really clean computer.

Thanks