Well my 700 froze up 2 more times and had to reset it , too bad they wont let you register the unit online they make you fill out a louzy post card and send it snail mail, well I guess some one has to give the post office some work
I'm assuming this unit is plugged into a lighter socket and not hardwired?
If so, and if you get a chance, try it in a different vehicle and see if it still freezes up. Some vehicles don't always put out "clean" or even sufficient power to the lighter socket.
The McNally unit might just be a little more sensitive to it than other brands.
Just trying to eliminate a possibility.
I too have high hopes for this unit and was seriously thinking of purchasing one, especially now with the new "E" revision, but to hear you are still having problems, I will wait. Please continue testing!