I'm finding the nav. system on my o7 limited tribeca hard to use. First of all, I can't figure out how to turn it off. It seems to always require a destination, and the only thing I can do to avoid it binging and trying to redirect me is to turn the sound off. Does anyone know a way to tell the computer "I don't need help this trip"? Also the only time I've tried to use it, thr route it took me on used only surface streets, even though the freeway and a tollroad were nearby and I had entered "allow tollroads". Is anyone having much success with theirs?