2007 Macbook overheating and shutting down

Have you run the Apple hardware test, to see if it identifies any hardware issues, like a bad sensor? You'll need your original OS X disks that came with your system.

Do you have iStat Pro installed, so you can monitor and perhaps isolate what's heating up?

As you watch the temps, do any components increase more than others? Does iStat tell you that the hard drive, for example, is heating up more than other components or the ?

Looks like this is a dead post, but I thought I'd chime in as well. My 2007 Macbook is getting to the point I can barely get on the internet anymore. Streaming video can kill it in a half hour or less, and just surfin the web with 4 or more tabs open gets the fan spinning up lik it's going to go into orbit.

Just so we're clear, I'm also broke but unlike the OP I'm not resigned to buying a new Mac if they straight up stop functioning after 5 years of service. At least all the Windows machines my family has and never throw out *run* slowly.

It seems like all the fixes offered to the OP seemed to say nothing was wrong with his computer. Is this considered normal? Is this that common of a problem? And Mac has no way of fixing it?

OP mentioned that he has 80GB free on his hard drive I have only 2 (of 120) free. Could that be the problem? Or at least contributing?

I have the same issue and don't really have a solution for the original poster here. The solutions that I've found that work the best is, to replace the fan and then replace the thermal paste. However, this has only resolved the issue slightly. My next option was to install SMC Fan Control and have it set to run max.'ed out all of the time. A little noisy but it seems to help. I try to only have one browser open with ClickToFlash installed to control things coming in from the browser (stopping unwanted Flash ads/banners from playing automatically). Then the last thing that I've done to help is to purchase one of those reusable freezer gel packs from my local drug store and simply place that under the machine at room temperature to help discipate heat, making sure that the exaust from the fan coming out the rear is not blocked in any way. I still get overheating and involutary restarts under heavy use, but now I can pay attention to the internal temperature (SMC Fan Control has an option to display temps & settings in the menu bar) and adjust things accordingly in my usage of the machine. The involutary restarts tend to happen as the machine approaches 180 degree (F) or so.

My hunch is, that as Flash gets ever more-and-more processor intensive with progressive iterations, it's hard for these machines to keep up due to the fact that they have no separate GPU and that's where the life of the machine's lies. It's simply getting too old to handle the greater capacity needed by Flash during video play back. It's just a hunch but, it was a known limitation in the design of these (and similar) machines when Apple elected to go with a processor that also handled graphics duties all on one chip as opposed to spec'ing and installing a separate GPU.

The good news is, that when I'm not streaming any video or doing video intensive things, the machine works and behaves just fine and does not tend to have any overheating issues with all of the fixes I've mentioned.