IS it coded properly for your car?

Check that first and code the nav as required using NavCoder.

Also try the following:
Delete entire address book and last destinations
Load an OS from an OS disc prior to V22, then reload OS from V32
These points will clear memory and rewrite memory

Otherwise if problem still exists then it is corrupt memory.

I didn't know the unit needed to be coded for a car. We must assume that hasn't been done. I need to buy a cable for NavCoder, right? What needs to be recoded?

I'll try the downgrade and upgrade process and get back to you.

I wonder if it's one more thing. I don't have the GPS cable hooked up yet. I have an e39 touring which, it turns out, doesn't have the Trimble unit in the same place as the saloon. I had to order an extension cable. Of course it has to come all the way from Germany and will take a month to get to the States. Anyway, could that be the problem?

The main settings to change are to match your radio module, other settings are really to do with telematics.

Of course with no GPS antenna connection the GPS won't know where it is.
SO it won't initiate in the right position, and it won't track the vehicle position accurately at all.

You could also order an extension cable locally, when I worked on Tourings I just got an SMB coax extension cable made locally for around $45 NZD (around $23 USD)

I downgraded to v21 and then back to the latest version. It appears to be working properly now. Thanks for the advice.

The radio seems to be working just fine. Can I assume the unit is properly coded then?

Yes, I know the GPS won't work without the cable. I was quite surprised to dig into the car and discover the Trimble unit wasn't in there. Guess what I said. :-) I already ordered the cable from BMW (at much more than $23) so I'll probably wait until it shows up. Still, can you tell me more about what the cable is like? It looks to me like there's a proprietary connects on these things. How would I make one?

Did you look properly for the GPS receiver?
It's mounted under the plastic floor panel in between the spare wheel well and the rear seat.

Cable: black coax cable, around 4mm diameter, fitted with SMB-male connector one end and SMB-female connector the other end.

Nothing proprietary about it at all, it is industry-standard SMB-connectors and 50-ohm low-loss coax cable such as LMR100.
You won't find it at your local hobby store, but any good RF cable place that supplies the cellphone base-station industry can make one for you. You need the proper crimp connectors, so unless you work in the industry you won't have the tools to make the cable yourself.