Back around the end of August I grumbled at some of the flaky behavior from Time Machine. Since then Apple has released a couple of updates that purported to improve Time Machine's behavior. (I'm now running 10.5.6.) Two weekends ago I rotated external backup drives; this is usually a source of frustration as Time Machine mysteriously didn't like the drive I was rotating into service. I use the same drive mechanism and same enclosure for all my backup hard drives, but this one drive just seemed to bring out the worst in Time Machine. Sometimes Time Machine would refuse to backup to the drive at all, while other times the backups would mysteriously fail.