I thought I would mention that WP-Polls is breaking the text editors in the edit membership level admin area. With it disabled you can once again edit membership descriptions.
The error is: Uncaught ReferenceError: pollsEdL10n is not defined
It seems for now you can just turn off WP-Polls, make changes, then turn it back on.
PS I also posted on WP-Polls support board as well.