You have Symantec's Backup Exec installed on a machine with a tape drive attached; The tape drive can only be accessed through Backup Exec. No Acronis or Microsoft product (e.g. NTBackup) can access the tape drive:
Backup Exec takes exclusive control over the tape drive.
As a workaround, uninstall Backup Exec. This should free the tape drive and let other software access it.
NOTE: Applicable to Windows Server 2003:
Since Symantec software affects Windows Removable Storage Manager (RSM), you might need to rebuild RSM database to clean up all the traces after removing Symantec software:
Stop the RSM Service
- Start -> Run -> services.msc; On the Services window, right-click on the Removable Storage entry and select Stop.
- Delete the RSM databases from %SystemRoot%\System32\NtmsData;
- Restart the RSM Service: Start -> Run -> services.msc;
- On the Services window, right-click on the Removable Storage entry and select Start;
- Put a new tape (or a tape that may be overwritten) in the tape drive;
- Hit Start-Run and type in compmgmt.msc to open Computer Management;
- Navigate to Storage -> Removable Storage -> Libraries;
- Right-click on the tape drive, select Properties and uncheck Enable Drive; Click Apply;
- Check the Enable Drive box again; Right-click on the tape drive, and select Prepare.