Comment 94 for bug 61381

Follow up...
Turned off Software Sound Mixing seemed to work at first. (No longer hung for several minutes starting Gnome, no more error message)
Other strange things started happening though.. Clicking the shutdown button on the panel caused it to freeze. Had to kill gnome panel.

Eventually I kill -9'd NetworkManagerDispatcher. Haven't had any problems since. Even after a reboot.
Seems to be network related, as others have stated the problem went away while not near a wireless access point.