We've just started discussing this on the mythtv list and the common thread seems to be mythbuntu.
mythtv-setup seems to be freezing on exit. It seems to freeze up when I get to the "If you've added or altered..." screen with the ok button.
Some on the list think it might be the mythbuntu wrapper around mythtv-setup.real.
Anyone else seen this in 0.26? I guess it can be hard to diagnose since many of us don't use mythtv-setup for months at a time.