I had an annoying case this morning where Backup Exec was refusing to write to a removable hard drive after it had got to the point where the disk was full. Even deleting old data on the drive, restarting services would not get the software to continue writing to the drive which now had 250gb of empty space.
In the end, right clicking on the device and selecting pause, then right clicking and unpausing the device fixed the problem. Simple when you know how but frustrating when nothing else seemed to work!