I tried verifying and repairing both disks, comes back green. Still fails,
8/14/12 10:59:06.611 AM com.apple.backupd[27500]: Stopping backup.
8/14/12 10:59:06.627 AM com.apple.backupd[27500]: Error: (-34) SrcErr:NO Copying /Library/iTunes/Movies/Jasmine - Year 2.m4v to /Volumes/My Book/Backups.backupdb/koe/2012-08-14-095326.inProgress/576367C8-0B1B-4552-B680- 9A908F9E1EC8/Macintosh HD/Library/iTunes/Movies
8/14/12 10:59:07.412 AM com.apple.backupd[27500]: Copied 545956 files (90.71 GB) from volume Macintosh HD.
8/14/12 10:59:07.412 AM com.apple.backupd[27500]: Copy stage failed with error:28
I tried deleting the file in question, but next backup fails on another file from same directory. Quit iTunes, same result. This only started happenening after upgrade to Mountain Lion, I haven't had a successfull backup since
Thanks in advance