I am running Symantec Backup Exec 2010 SP1
I am running daily backup to tape and the attached tape device is HP 1/8 G2 autoloader.
Everything was working fine and suddenly the job started to fail with the error in the attached printscreen.
After the failure I found that the Device bacaem "Offline"
I made sure that the cabling are ok.
Device is ok, i can not find any errors.
Run vendor diagnostics (HP L&TT tools) against your tape drive.
Secondly, these KB articles may help as well -