Suddenly Time-Machine is giving me grief. In the past I might get a "backup failed" message. Not a big problem, I'd just hit "backup now" and everything corrected itself very quickly. Not now...

If I hit "back-up now" (from menu bar) I get a message "preparing backup...". My external hard drive continues to churn, but I am stuck in this loop for extended periods of time. (Occasssionally, after 10 min of this the backup will complete.) If I hit "stop backup" I get a message "backup stopping" but the HD continues to churn. Often I have to reboot to settle things down.

This is all relatively new behavior. (I have repaired the disk directory and permissions with Disk Warrior, it didn't help)

Any thoughts?

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