Forgive me for saying this because its not the fix you are looking for, but in case you haven't tried it, the CarHome Ultra app is awesome. I liked it way better than the stock car panel app. 3 custom pages of 6 large icons you can set, landscape dialer, speedometer, compass and weather options, plus automatic shut off of wifi and the app when you turn on and off your bluetooth headset (that's optional of course). The developer is responsive and actively working on it. Up soon is a optional speed warning if you want it to let you know when you accidentally hit a certain speed. Car panel looks great but I've come to really like the CarHome Ultra app.
Sorry I don't have a fix for you but at least you know you have options. Did you try the old pull battery, sim card, and sd card for two minutes trick? who knows! Good luck!