Problem applying W2K Service Packs

Hi,
I upgraded a NT4 (SP6) server to W2K Advanced Server. After a couple of reboots things seemed OK.
Problem now is I cannot install a Service Pack, either 1 or 2. I have tried several things, as described below.

I have admin privileges; Ihave not stopped any services, including Exchange 5.5.

The first message during the installation process is "The procedure entry point I_CryptGetAsn1Encoder could not be located in the dynamic link library CRYPT32.DLL."

Then I click OK and alittle later I get a window saying "Failed to install catalog files."

When I try to do the SP install from files or from a CD, I get nothing in the error log. However, the one time I tried the update from Windows Update, I got the following message:

"...The following information is part of the event:
V3_2|4554|INSTALL|Windows 2000 Service Pack 2|1,10,0,0|
2002-03-12 20:38:09|1|FAIL|0x80004005|Unspecified error|."

(Also maybe noteworthy is that in this one time trying from WindowsUpdate, I did not get the message about "The procedure entry point I_CryptGetAsn1Encoder could not be located in the dynamic link library CRYPT32.DLL.")

Efforts so far...

In examining literature and comparing to my own configuration, I found that my setreg 10 was already false, and that I already did have the Microsoft Root Authority certificate. I re-imported said certificate to the Trusted Root Certificate Authority, to no avail. Q281458 also mentions expanding a NT5FIL.CA_ from the SP files and then (in safe mode) copying it to two directories that the Q article names. I'd try this too, but in the files extracted via "w2ksp2.exe -x" there are several NT5FIL.CA_ files. Which one is the right one to use. Or, should I copy sucha file from a W2K member server which is already at SP2?

I do not have Certificate Services installed, but I don't think that applies.