800B0001 = Unknown Trust Provider
A common cause of that, is failure to apply the relevant updates to the WSUS server itself, e.g. KB 2828185 or KB2720211 or KB2734608:
http://social.technet.microsoft.com/Forums/en-US/home?forum=winserverwsus&announcementId=203b9507-068d-487b-b72a-b8b789037a34
Is your WSUS itself patched and updated?
Don
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