Hello,
We would like to know whether you are using 9.1 If yes then please verify whether your issue is the same as explained in the technote:
After an upgrade, VERITAS Backup Exec (tm) for Windows Servers displays "Overwrite Protected Until" as "Infinite - Don't Allow Overwrite" when a piece of media is no longer appendable due to being full or damaged.
If yes please install SP2 which has hotfix 3 included
http://support.veritas.com/docs/275247
Thanks,
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