storprop.dll not being copied to system32 from driver.cab?

I'm having the strangest problem with a particular computer running my
standard unattended XP (a setup that has been used trillions of times
on every kind of PC here in the office without any problems) with SP2
slipstreamed along with the latest intel chipset and SATA drivers.

Anyways the problem is that for whatever reason, storprop.dll is not
copied from the driver.cab to system32 on this particular PC and thus
I get those silly "device installer" errors for all my storage devices
(CDROM, harddisk) and asks to install a driver that it will never
find. I say "silly" because the hardware works fine and is accessible
from XP. Manually copying storprop.dll from driver.cab in the driver
cache folder solves the problem instantly (after telling the device
manager to scan for new hardware).

Troubled PC specs:

E8400 (45nm intel c2d 3ghz)
DX38BT (retail branded Intel desktop board w/ x38 chipset)
2GB DDR3
1TB RAID1 (2 samsung 1TB's) on the integrated ICH9R
Radeon 3870
LiteOn 20X DVD+/-R

I have verified this very same unattended XP install image on several
other PCs, all very similar to the troubled one (q35 and Q965 based
intel boards with integrated graphics and AHCI or RAID mode) and
installs without issue - AND - storprop.dll is where it should be in
system32.

What's going on? Could this stem from hardware? My only workaround at
the moment is to have storprop.dll copied from a batch in or svcpack
T-13 or RunOnceEX - but obviously I want to get to the root cause
rather than dance around it.