I am having the same boot screen problem with my Z1. I live in Arizona and a couple weeks ago it started for the first time. Now it's happening more often as the heat is increasing here.
I park my car in the garage at home so when I leave for work in the morning it has never frozen up yet, but when I park in the parking garage at work, when I leave for lunch, or when I leave for home at night it happens frequently now.
I also did the CDDB update discs, but like I said, I haven't noticed any problems at all until summer started here. It seems like it's definitely related to the heat, bu