Sounds like something you learned the hard way.

And dude, switch to decaf. :D

Could this seriously be related to heat? It just crashed again. I took the cover off and started a fan blowing into the "guts" of the computer and was only 5 minutes or less it started again.
They said they were going to clean the computer (dust etc).

Whereis it? I know what a heatsink looks like, I don't see it. I can post a pic if the computer stays running, LOL

OK I do see it now, really large aluminum colored. I don't think they cleaned the inside like they said they were going to. Still don't know how what they did would be related. To me the fan seems to be pretty weak. I might shut down and see if I can get to it. I do have a small fan blowing towards the heat sink now.

OK I figured it out pretty well, I got the heatsink off, didn't realize how easy that was to do. What I did is used the only thing close at hand to do this; I have some of that white thermal paste that they use on w140 blower motor regulators. I didn't clean the old stuff, just smeared some of this on the contact area and will see what happens. I am not totally convinced the fan is blowing at full speed though, will "see how it goes in testing". I did vacuum around the general area as well. Is there usually just one fan?

Paste I used is German stuff by Seifert Electronics it's called KF-400 and it is silicon.
I have the cover off and am using the small fan as well, hey my computer has an aux fan!

Well so far so good with my extra cooling measure, about to shut it off to watch a TV show, so will see how long my wife lets it sit out of the computer desk with no side cover and the small fan next to it.

You need to clean the old stuff off. It may have helped, but not nearly as much as if you had cleaned all the old hardened stuff off. Once thats done, if it does infact fix the issue, switch to arctic silver. More than likely the big fan you added will not be needed

I use a external cooling device for my notebook - two small fans in a thin platform. My machine used to leave the table hot. Not now. Heat kills. Is there any sort of external cooling arrangement that might help imacs?

Would some low pressure compressed air have helped the cleaning maybe?

So far it is working, Here is the paste i used:
Seifert-Electronic - Products

Well this is good, have toget ready for work now, so it held up really well, I am still suspect the fan is weak but have nothing to compare it to or really to test it even.

When places "clean" your heatsink they just spray compressed air on it. You need to visually get in there and remove lint, dust, cat fur, etc.

If your car was overheating, would you just slap a miracle-in-a-can and keep driving it? Or would you replace the $30 thermostat that is causing the overheating?

As other have said, get in there with some alcohol and qtips, clean the heatsink thoroughly, and slap some artic silver on it following the directions. Retail it's $12 at RatShack: Arctic Silver 5 Thermal Compound : Computer Cooling Systems | RadioShack.com
Online it's $8 Amazon.com: Arctic Silver 5 Thermal Compound 3.5 Grams: Computers & Accessories

Assuming this is a desktop, if you want to upgrade the heatsink there are a huge number of aftermarket copper coolers with large, silent fans. If you give us some more info on the machine we can help you pick one out. For your needs $25 would be a good estimate.

FYI-if the CPU thermal compound was junky you should probably replace the compound on the north bridge and GPU. You would be surprised what a difference that can make.

If you want to go to a clean install of XP and you need a cd I can mail you an unmolested copy.

Thanks to all for the offers and tips. It is old enough that I think before spending a lot of money I would go to a new computer. Will see if get any more troubles with the "aux fan" and go from there, am more curious about the fan being a problem over the heat sink itself.

I would definitely consider pulling the heat sink again and cleaning and I'd probably use the paste I have, nothing else to do with it anyways and I think it does the job. If I was in the business of doing this I'd get the good stuff.

Again it is old, it is a DELL Dimension E510

Did it again. Is not saying the bit about "page fault in non paged area" any more, but looks essentially the same (this on the blue screen of death).

Pulled the heat exchange, and did clean off nicely with rubbing alcohol and applied the paste i have.

Will see what develops.
Milwaukee PC agrees with possible overheating diagnosis, they said check "all" the fans, I didn't know there was one in the power supply, that one is working as well.

Computer was still busy shutting down when i pulled the heat exchanger (sink, sorry), then noticed that fan took off running really fast, I didn't know it has different speeds, it will spin like a bat outta hell if it has the mind to, so not as concerned about the fan as I was.

Will continue to surf and see what develops next.

Surfed about a half hour (since my last post) and no fail yet and that's with the cover off but no fan blowing in to the box. Opened up multiple pages at once, played a youtube video and went to other sites, may be licked, will cross fingers.

Maybe needs a new vortex homogenizer on the flux capacitor.