Backup exec NOT APPENDABLE MEDIA FULL...

Hi, running 11D 7170 on Wind2k3 server.

I have reached the end of my rop on this one.  This is the millionth time I have to recreate backup jobs.  Jobs run fine for a long time, I have them ALL set to OVERWRITE the old jobs after so many weeks, then suddenly they start the "NOT APPENDABLE MEDIA FULL" stuff for no reason and my backups all fail.

I backup to external hard drives, not tapes, but swap the HD's like tapes in a rotation.

I have chaged setting in options etc etc, it all starts again.

Is there a solution for this?

Thanks,

MP