After uploading all of our server logs to Blackberry support on the weekend, we received the following reply today:
Thank you for contacting BlackBerry Customer Support. The log files did not pin point the error that is occurring. It appears it may be a local port conflict on the BlackBerry Enterprise Server and the Small Business Server. The installation guide does point out that the BlackBerry Enterprise Server 5.0 is not to be installed on the mail server. You do have messaging working but not the Monitoring Service. We recommend you try and install the BlackBerry Monitoring Service on another machine. We cannot guarantee this will work as the BlackBerry Enterprise Server is not installed in a supported environment. See page 19 of the attached Installation Guide.
So, it looks as though we will need to look at repurposing the old SBS for BES, or there may be some other options to discuss with our client.
Lesson learned. :)
Microsoft Small Business Specialists
Co-Author: SBS 2008 Blueprint Book