Getting a STOP error on Vista boot (PAGE_FAULT_IN_NONPAGED_AREA)

I'm trying to boot into a Vista 64 bit machine and during startup, right after the progress bar starts scrolling back and forth, it BSOD's with a STOP error 0x00000050 (PAGE_FAULT_IN_NONPAGED_AREA). I have tried the following with no success:

• Booting into safe mode (same BSOD)
• Doing a system restore to a previous checkpoint (it says there are none, which is odd)
• Running a memory test using the diagnostic tool - passed
• I was able to get to the command prompt with the diagnostic tool and can access the boot drive. I copied off the most important files to another drive.
• Ran a chkdsk with the repair option - it says it found 5 unindexed files, and fixed them, but the problem remains
• I disconnected all external components except the keyboard, mouse, and monitor. Problem still remains.
• I tried just running it with one stick of RAM, then the other, just to make sure it's not a RAM issue. Problem remains.

I think the next step is to completely re-install Vista. Am I missing something?

Excellent troubleshooting work.

In particular, if you've run the memory test diagnostic and it is passing, then I can't think of any other resolution than reinstalling the OS.

(and even then, I'd be wary of bad hardware based on everything else you've ruled out -- a clean OS install is a good smoke test, because if you can't finish a clean OS install, you almost definitely have bad hardware at that point)