Cryptographic Service will not start Error 123

Archived from groups: microsoft.public.windowsxp.help_and_support (More info?)

Iam running XP Home on an HP Pavilion.
I have tried all of the fixes such as disabling then rebooting and set to
Auto. I have re-registered the .dll's assoc. with cryptsvc and I have run
sfc/sannow. I did notice that there were ALOT of messages in the Event
viewer from the scan that some files were not able to be restored. In
addition the scan took almost 2.5 hrs to run. My only symptom is that the
CryptSvc will not start and thus cannot update from MS.com, otherwise PC
seems to be running fine.

When I try to start the Crypt. service I get "Error 123" Invalid extension,
or label or something to that effect
I have read on MS site that NAV and McAfee needs to be disabled to access
the Windows Update site. Has anyone else found this to be the case?
Thanks