I recently lost power overnight with my computer up and running, external hard drives plugged in, and in the morning my login screen had the "Device Removal" error as if I unplugged the disk without ejecting it.
The disk in question was a brand new drive (1 or 2 months), and I created 3 different partitions on it: a clone of Snow Leopard from my machine, a partition that had the old Snow Leopard backups on it, and a third partition that I was going to use strictly for Lion Time Machine backups.
After logging back in, my snow leopard partitions mounted without fail, but the third partition I was using for backups failed to mount and returned "Invalid key length" after scanning it with Disk Utility. The partition was "unrepairable" as well and returned the error "Disk Utility could not repair the drive. Read only blah blah copy files off it and reformat it as soon as possible."
Is this entire partition bust? Why does it still let me mount my other ones without problem? Is the drive OK? Help!