You didn't mention which graphics card you're using. For some older cards, the latest drives are not necessarily the best ones, and they might not be the most stable ones, either.
I'm running 66.93 drivers from
http://www.nvidia.com/object/winxp-2k_archive.html
atm with my Fx5200 card, and it works just fine.
Not being able to restart for 5 minutes points to a thermal problem: either graphics card or CPU had to cool down before it initialized correctly again. Core driver crashing points to graphics card, while "forgotten" speed settings points to CPU not starting "correctly" and therefore set to failsafe speed (PCI bus set to 50 Mhz, etc.). I have, in rare cases, seen such errors which faulty memory chips or failing EPROM, too, so 'debugging' can get pretty complicated...
Was there any special beep code from BIOS during the failed startup attempts (provided you have the internal speaker connected to the motherboard, oc.) ?
SW