Gee...I'm not sure. I can think of a couple things you might want to try. But, depending on the size of your installation and programs installed, it might take a long time.
First, clean out your system by uninstalling programs you don't use anymore. If you have beta software, uninstall that, too (in case it's one of the culprits). Also, go <A HREF="http://www.langa.com/downloads.htm" target="_new">here</A> to read how you can "scrub" your hard drive clean - for free! This takes care of wasted hard drive space and the registry. Also, run a scan disk and defragment the whole thing.
Next, download all the updated drivers for your hardware. Download the most recent version of software that you can find. Recent versions fix problems that might've plagued older software revisions, so the newer one might also reduce the crashing.
Now, this is tricky. I haven't tried this, but I read another thread here that someone has and it worked. Uninstall your hardware devices that need drivers, like your graphics card, sound, modem, printer, etc. Then, reboot and reinstall them with the latest drivers you've downloaded.
I'm not sure how much time you save by going this route. But, at least with a clean install, you're probably going to have better results.
Windows is getting better, with XP being really good. But if you really use and experiment with your machine, it is only good for 6 months or so. After that the registry and such is so messed up it is not worth fixing. Backup your data and start a new OS life with a fresh install.
I don't know everything, but some things I do know. - Goethe
There is a way, but as btvillarin said, it's quite tricky and in most cases frustrating. You should do all of what btvillarin said, and on top of that, try and get the latest versions of all your programs, and get the latest patches for Windows, and other Microsoft products (IE, Office). If you really do not want to reformat, then you should do all of these things. If it still crashes, you may have to manually find out the cause (that's a grueling job). If you don't know what you're doing, you could mess up your system even more. Manually finding out the problems could involve navigating the registry, Windows system files, and/or getting lost in all of the different configuration options. Now, it probably sounds confusing, but it works. I've been running my Win98SE install for about 8 months. It's got lots of junk on it, but runs very stable. I've had to manually optimize and tweak the system like mad to get it to run this way, but it was worth it. The only problems on my computer is Kazaa Lite which crashes frequently (wasn't programmed very well) , and a stubborn Winamp Skin which crashes Winamp. Other then that, my computer is as solid as a rock.
Montecito & Chivano; Intel's Big Guns.