hal.dll missing repeatedly in XP pro SP3 after updates - NO BOOT

Last week, after applying some of the usual security and general XP updates that are downloaded via Automatic Updates, the computer rebooted and gave the message:
"<windows>\system32\hal.dll is missing or corrupt"
The computer would not boot from any of the options via F8 (including "Last Good Config" and "Safe Mode")
I booted from the XP CD and started the Recovery Console.  Confirmed hal.dll was present, then tried the following (rebooting after each try):
1) copied hal.dll from \windows\system32\dllcache to system32
2) Deleted boot.ini, then ran bootcfg /rebuild
3) I expand hal.dll from the CD
4) ran fixboot
5) Finally did a repair install and the system booted up fine, everything looked good.  Went to Microsoft Update and downloaded the 79 fixes since the SP3 cd was issued.  Rebooted and got the hal.dll message again.
Did a repair install again.  Installed all the updated except the most recent ones from the last 2 months.  Seemed to be working.  Installed a few more updates, then it happened again.
Did another repair install and ran anti-virus (avast) and anti-spyware sweeps (I had just scanned a week before the problem).  Found 4 viruses, one in the Software dist download folders.  Deleted all the Soft Dist Download files.
Everything looked clean.  Then it happened again.  I think my wife may have applied some updates not realizing I was holding off.  The time stamp and size of hal.dll always look fine.  The boot.ini always looks fine.  If I expand hal.dll from the CD and reboot, it gives me another dll that is missing or corrupt.

I am getting tired of the repair install (doesn't seem that fast the 5th time), so any other ideas on where to look would be very appreciated.

Specs:
Dell Latitude D505 (laptop)
XP Pro SP3 - FAT file system
1.5GB RAM
250GB HD (replaced about a year ago)