Thanks to all who responded. It looks like my problem is really
Garmin's problem and maybe even a GPS nav problem (given the Toyota
built-in system with the same problem).

One other crazy thing: When I was on a freeway, it once told me to make
a right on Main St (or some other road). But there was no exit there!
I'd have to go off road to do that!

Hopefully these things will get better.

Martin