error (Index ('CSCOST.DAT',) already covered, skipping)

[Jeb Campbell]

Using rdiff-backup 0.7.6 (also occurred with 0.7.4).

This error occurs on a few files and prevents the file from being backed up:

Error 'Index ('CSCOST.DAT',) already covered, skipping' processing 
CSCOST.DAT
Skipping CSCOST.DAT because of previous error

The file is readable by the backup user (and even owned by it) to see if 
that was the problem, but no luck.  Could have 0.7.4 messed up some 
files, and I need to delete the the files it won't backup to get it 
going again?

Thanks,
Jeb