I finally got around to upgrading my Mac Pro desktop to Snow Leopard a
couple of weeks ago, but I didn’t reconnect my Time Machine backup drive
until late last week. When Time Machine fired up it would endlessly hang
while starting the backup, or hang on a “clean up” operation, or in some
cases would crash the Finder entirely and force me to have to reboot the
machine.

My backup drive was connected via firewire, so on a whim tonight I
reconnected it via USB. So far no problems. I searched around a bit and did
find several references to firewire problems after Snow Leopard upgrades,
so I’m hoping that was the culprit. Just thought I’d post this in case
anyone else was having similar problems.