Error Updating Bulletins: "Error: Signature verification failed for: Post XML Update SQL"

Hello,

I have recently installed VCM 5.6 in a single server configuration.  Currently, there are no Windows bulletins displayed within the Patching slider.  (I currently only have Windows servers.) 

I go to Windows > Bulletins > By Bulletin, and selected the "Check for Update" Button.  I receive a message stating that there are updates available. So I click through the dialog boxes, and receive a message stating that the download job has been submitted to the pending queue.

When I check the job history, the job states that it has completed, but with the following error: "Error: Signature verification failed for: Post XML Update SQL."

Any ideas are greatly appreciated.

-Kay