VaultDR Online backup fails with "Failed to get Logical Drive Letter for partition... This partit (4045820)

Date: Jul 08
Product & Version: All NVBU
OS Version: Windows
Module & Version: VaultDR Online for Windows 2.3
Application version: N/A

Symptoms:
When running a VaultDR Online backup, it fails with errors inthe log similar to the following:

Warning 2008/08/05 11:11:35 1404 Data Plugin vdrtest Failed to get Logical Drive Letter for partition (1) of Disk (0). This partition cannot be backed up
Error 2008/08/05 11:11:35 1404 Data Plugin vdrtest Partition list is empty for device: Disk 0
Error 2008/08/05 11:11:35 1404 Data Plugin vdrtest Failed to get selected items for backup

Reason:
This error means that there was a problem obtaining the drive letter and/or partition list for a device. This usually happens when there is something "special" about this disk.