Why is Commvault regularly marking tapes bad after upgrading to Simpana 8?

Two weeks ago, a Commvault tech came in to upgrade Commvault 6 to Simpana 8. The process went pretty smoothly during the 2 day event. There were some issues to clean up at the end of the second day, but all seemed to be well during the next 2 days. Since then, I have had tapes regularly marked as bad though I had no issues prior to the upgrade. In the 1.5 weeks since the upgrade, I have had 8 tapes marked bad. Once they are marked bad, it becomes a chore to get the tapes out of the library. We have a Dell ML 6000 LT03 library running firmware 520G.GS003. I have talked to Dell about the situatino and they took copies of some logs to review. I have run an exhaustive detection and marked all media agents as fixed due to some errors that the Dell tech found. Most of these tapes have no read/write errors or such. I have tried exporting the stubborn tapes via the ML6000 and Commvault (most of my work is done through Commvault). Last week, I was able to remove 2 stubborn tapes via the ML6000. Yesterday was I was exporting tapes for offsite, 2 tapes were marked bad. I spent the afternoon trying to move the tapes into the library door with no success. This morning I was able to move one into the door though when no matter how I export them, it always tells me export in progress and shows the tapes in the window. There will even be a comment in the event viewer that the stubborn tapes were moved, but when I get over to the other buildig, no tapes. Thoughts? Thanks.