update problem continues

cant update even manually by KB
I got in the setupapi.log:
[2006/02/16 19:30:06 1684.2]
#-198 Command line processed: "E:\tmp\z\913446\update\update.exe"
#E361 An unsigned or incorrectly signed file
"e:\tmp\z\913446\update\KB913446.cat" will be installed (Policy=Ignore).
Error 1722: The RPC server is unavailable.

what causes "The RPC server is unavailable." how to fix that?
the service for Remote Procedure Call (RPC) is started and is automatic

I even make sure Remote Procedure Call (RPC) Locator is started.
this does not require net bios helper, or does it?