Do you service computers running Windows XP? Do you occasionally rebuild them with new components? Then keep the following in mind.
We had two PCs at work that we rebuilt with new CPU/board/RAM, noticed they were only running Service Pack 2, then as a normal part of servicing we ran the installer for SP3. Both of them seemed to install fine, but when we came back they were stuck at a blue screen – 0x0000007e.
This rung a bell for me, as we’d had this sort of thing happen before, and I managed to remember: If you have an Intel PC running XP SP2, then rebuild it with an AMD CPU, then install SP3, it will BSOD. It’s still trying to load an Intel-specific driver that causes major problems if you switch to AMD, so as per this Microsoft KB article, you need to boot it into safe mode, fire up regedit, and change the value of the following registry key:
…from whatever it was to the number 4. Reboot into normal mode, and away you go.