I had a weird error on a rev drive backup which wouldn't let me do anything to the rev drive - I was unable to backup, catalog or do anything else useful with the drive. I was getting the error message "An error occured while processing a B2D command. Change: MoveMedium() Attempt to Lock Slot Failed (Path to file.lck); Error=112
If you enter "Attempt to Lock Slot Failed" you get no results back from Google or Veritas (thats not suprising on the latter) - the only thing similar states that the disk is full. In my case explorer shows 2.8mb free and it is set to overwrite in Backupexec anyway.
I'm not sure what I did to get it working in the end but the following 3 things seemed to do the trick when done at the same time.
1. Remove the drive and put it back in again.
2. Dragged the oldest file to the scratch media (this seems to solve a lot of BE problems)
3. Kicked off a backup job to restore a small file.
Hope this helps someone else.
I've been having the same problem. I'll try your suggestion and see if it helps.