This is a rotten problem to have. :(

Start the computer in Safe Mode and see if it still crashes.

To start in safe mode: Turn on computer, poke (not hold) the F8 key repeatedly until the boot choices menu shows up, Select (using cursor keys) to start in Safe Mode. Next screen, choose your installed XP to startup. After awhile, you will have a choice to continue into Safe Mode or perform a System Restore rollback to an earlier date. Choose to continue to start in Safe Mode.

There won't be a lot of things you can do in Safe Mode, but run whatever will run that you have experienced the problem with. It may have been while printing, or playing a game, but exercise the computer to try to make it crash as before. If it crashes, remember what you were doing at that time to invoke the crash. If it crashes without you doing anything, then I would be suspecting a bad memory board, but this is not a certainty.

While you are in Safe Mode: Click "Start" then "Run" and enter "sigverif.exe" (without quotes) and then click Ok.
A program will launch to scan all system files and check if they are "signed" or not. These files will include device driver files. All unsigned files will appear on a list. If you have the patience, write down the list and post it here. I don't need version numbers, just names. A bad driver is the most highly suspected cause of your problem and an unsigned driver is at the top of the suspect list.

If you are an advanced user:

If it just won't crash in Safe Mode, shutdown and restart normally.
Make a new restore Point now.
Disable devices that the computer can run without one at a time.
Start by disabling devices that have drivers showing in the unsigned system file list first.
Exercise the computer and try to make it crash. If it does, the device you disabled is not the culprit.
Re-enable that device and disable another one until you disable a device and the crashes stop happening.
If you go through all devices that can be disabled, then the problem is going to be harder to find, but we should start with what is suggested here for now.

There are many devices under "System Devices" and some of them may cause your computer to stop functioning.
If it stops, restart and poke the F8 key and choose to start with the "Last known good configuration" then continue the search for a bum device (driver) but leave the one that stalled your machine alone.

If you are interested in learning what causes that particular error, there is an excellent write-up on it that you can see by clicking