Case 1.) Jaunty to Karmic beta. Went to sleep with laptop on, woke up. Couldn't read/write files. Rebooted. Ran a huge fsck. System was permanently borked.
Case 2.) File system encryption brings you to emergency root shell. Running fsck solved it. Unsure what happened because who the hell monitors this stuff.
Case 3.) 64-bit flash is fubar'd. You gotta go grab the 64-bit version from adobe and symlink to it.
The truth is, Karmic was not a smooth upgrade in the big picture.
Ubunteros can't gloat at Windows 7 being a bitch to upgrade.