We weren't quite done with the VSS issues.
In this bulletin, MS tells us the Exchange VSS writer is turned off by default in Small Business Server installations. This is to permit the backup wizard to properly backup Exchange and the system state in the same job.
However, when using a third party backup solution, Exchange VSS support may be needed. Please note, MS cautions you twice in their bulletin about using the SBS Backup Wizard to backup Exchange and system state with Exchange VSS turned on.
So, if you really want to use SBS' Backup and a third party backup solution on the same box, turn on the Exchange VSS writer and make sure you don't run SBS Backup to backup the system state and Exchange in the same job.