Security Updates fails

[Bob Collina]

One of our 4 XP Pro computers fails to update
with Q817287: Critical Update
and 811493: Security Update
(Athlon 2000 w/384K Ram)
Log file is below, Cryptographic service is running.
----------------------------------------------------
Service Pack started with following command line: -q /Z
***
InstallInfCatalogFile: Installing
e:\06e59edf5a048234f3a058596899fb\update\Q817287.c at as
_000000_.cat...
***
VerifySize: Unable to verify size: Source = NULL:
c:\windows\_000000_.cat
***
InstallInfCatalogFile: Installation succeeded.
***
DoInstallation: ValidateSingleFileSignature Failed:
STR_FAILED_INF_INTEGRITY
***
Q817287 Setup encountered an error: Setup could not
verify the integrity of the file Update.inf. Make sure
the Cryptographic service is running on this computer.
***
Setup could not verify the integrity of the file
Update.inf. Make sure the Cryptographic service is
running on this computer.
***