Hi, My Premium X after about 2 hours of use some functions stop working such as the voice directions, some items in the screen such as the route bar become empty the next exit display on the top disappears. Also the screen buttons become less responsive or slower. I have found the going to the menu and then back to the main screen sometimes fixes it, if that doesn't do it a shutdown and restart is needed then its seems to be ok for a while again. Last week I couldn't get it to shutdown easily by pressing the button on the back, the screen went blank and it was talking directions to me, I performed a power disconnect and it displayed 'No power shutting down to 8 secs' than went screen went blank (still talking to me), I powered it up again (screen still blank) than powered it off again this time it when to 1 sec. Third time it powered off and stopped talking directions. As I said its not happy. I dont really want to be going through this when I'm driving, Any suggestions would be greatly appreciated.