It sounds like the 96 errors are due to your media being frozen?
Then determine why the tapes are being frozen.
The following technote is for your 4.5 version of Netbackup.
It also contains valuable insight and is applicable to the newer versions.
Start with 'Media Logs' report to find reason for frozen tapes. Also check bptm log for errors.
'bpmedia' commands only functions against mediaDB database. If tape was frozen without any valid images written to it, the unfreeze command will clear the entry for the media-id from mediaDB (bpmedialist only queries mediaDB). You will still be able to find physical status of media using 'vmquery' command.
This is not a Bug mandeep. Netbackup freezes media because of some reasons; that details u can get it from that guide itself.
It is good and recommented way to keep the Master upto date, because now days netbackup palying in backup world, so we have to utilize the netbackup features by keeping backup setup upto date
There are some more guides like this. Here is an overview: https://www-secure.symantec.com/connect/forums/faq-depth-troubleshooting-guides-netbackup-5x
It sounds like the 96 errors are due to your media being frozen?
Then determine why the tapes are being frozen.
The following technote is for your 4.5 version of Netbackup.
It also contains valuable insight and is applicable to the newer versions.