If these are NOT imported tapes, change the Overwrite Protection Period of the media set so that the tapes have expired when they are due to be re-used (6 days for dalies, 27 days for weeklies etc
Also, if you have opted to have BackupExec eject the media after the job has run, the timer for the job will not stop (the job will not "end") until you respond to the "Remove Media" alert or lift the handle of a DLT type drive.