as Jadey already said my question with the notes client was not a recommendation.
it is from the domino point not recommended. you get various weired error messages.
here is the IBM statement to that: "Although IBM does not encourage running the server and client on the same machine, we do support it and there are cases where it makes sense (for example, an API program on the same machine running on top of a Notes client and data directory that is separate from the server install)."
the error message with the cross certification could be a problem with names of the client - would be my guess
i would say get rid of the notes client on the bes server...