backup failed: error 49

I backed up a larger folder with music files using the “full backup” with “simple copy” method. It went for a couple days and at 99% gave me error 49 saying “device not ready.” The backup seem to have succeeded, however. All the files are there. But I wanted to use this full backup as the base for further incremental backups. What went wrong?

Am I to assume from the lack of any responses to this and other posts that this forum is not the right place to seek help? Is this software even worth the trouble?

Please include more information, for example:

CB version
OS version and x32/64
Backup location
Folder size

Are you using the split backup feature for this large folder?
Are you able to make any backups, for example with small folders?
Is it possible that the music folder is in use or locked by an audio management tool?

Version 4.3.6.6

Windows Vista Home. Premium x32
Location and destination are external HDs with 3TB capacity

Folder size is 1.96TB

I don’t know what split backup is
I went back I tried backing up smaller folders. It worked fine. I think I even got the one folder that wasn’t backed up, so that now I have a complete backup.

I also successfully backed up another drive with similar data and size.

My question now is can I run differential backups or do I have to do another full backup from scratch before that?