Backups to HP LTO Ultrium 4 tape drive fails with “A hardware error occurred” error when using UMD.
Force Kernel Mode Drivers (KMD) for the tape drive. To force KMD set the following registry key:
HKLM\SOFTWARE\Symantec\Backup Exec For Windows\Adamm\DioDrivers to "0xffffffff"
"0xffffffff" means - Do not use new device discovery. This disables the new device discovery process and as a result forces KMD.