I, too, have only had it happen when I've been running visuals. I haven't had it happen since I've been in love with the "Now and Next" info screen. Perhaps it's related to the unit starting with certain visuals on the screen?

I had it happen to me this morning (beta 10a) when I started the car (to the Info screen, of course, no visuals).

Corby
SN#320,6-Gig Blue