I've noticed this, too. I'm not sure yet if it has to do with the visual (I've been running Hula Hoops since I got b10), but it seems every time I start my car now, Emma (thanks, Henno) plays a couple of seconds of music and reboots. This isn't a FULL reboot; it takes about 2 seconds and the bootup text scrolls up the display.
This started when I loaded Consumer beta-10.
Thanks,
Jason

_~= Dearing =~_
"WAY too happy about having #99."