Unfortunately, most of the advice given to this point has merely enabled you to pursue a wild waterfowl with fleet feet.
The symptoms described preclude most suggestions to this point. The problem is almost certainly one of the following:
1. A registry setting.
2. A driver issue, possibly even AGP or busmaster. Video is possible.
3. BIOS revision (least likely).
4. Hardware.
1. Are you able to confidently edit your system registry? More importantly, can you back up and restore your registry?
2. Do you know the exact model of your motherboard, including the revesion (e.g., ASUS P5A rev. 1.03b)? Who is the northbridge manufacturer (Square black chip about the size of postage stam on the MB, maybe ALi or Intel... should be in MB manual). Who is the Mfg of your Video card (model and rev. #)?
Who is your printer Mfg and did you install any printer drivers, or did MS install them all?
3. Who makes your BIOS (Version, obtained at boot time)?
4. Are you overclocking, or have you set any MB settings, or BIOS settings yourself? Shat is your cooling situation like... e.g., fans, chip attachments, usage of heat transfer grease/teflon. Have you upgraded any RAM yourself? What Make and model of hard drives do you use, and are you using full busmaster data transfers?
Some things you may not know, but with the above info, I might be able to spot the issue, but more likely some will be eliminated, leaving you to do certain troubleshooting yourself.
MS has made a mess of things in the XP world, and I could tell you tales of real-life foul-ups in their OSs. My general feel is that the issue will boil down to a driver/OS issue causeing the instability, and depending your your tech experience and time, you might be better off with an incremental fresh install, with minimal hardware initially. This can take a few hours, but will catch both hardware and software issues.
A CDRW burner can speed things considerably by preventing time consuming 2nd and subesequent base installs in the troubleshooting process.