0x800B0004

I am getting this error when trying to download updates for SUS on a Win2K
box. I can get updates from the normal windows update web site.

Manual Sync Started- Sunday, May 15, 2005 2:54:07 PM Failed
Updates Added:
None
Updates Removed:
None
Reissued Update(s):
None
Errors:
The catalog file downloaded from
'http://www.msus.windowsupdate.com/msus/v1/aucatalog1.cab' has a missing or
invalid digital signature. (Error 0x800B0004: The subject is not trusted for
the specified action.)
Sync Finished-Sunday, May 15, 2005 2:54:27 PM

Any ideas?

Joel