I have nav in all my cars and don't really use it on my phone locally here in Colorado. I was in Austin the other week and used it for the first time. It kept freezing after a few minutes and lost gps. I resorted to Google maps which worked great;. When I got home here in Colorado I deleted it rebooted the phone and reinstalled it. I tried it out driving to the airport on Saturday and when I got on E470 I noticed the phone was locked up on I25 still.