using schedule '0 23 * * 1-5' that a backup starts at 2011-01-21 23:08 (Friday night), which is okay. At 2011-01-23 00:00 (Sunday) it starts again and repeats every minute, which cause that every thin is on hold, because of the 'Prepare for shutdown state' during backup.
The other thing is that the backup destination are running out of space very fast.