OK, there are a few steps you need to go through to start the process, it's not as easy as just inserting the disc.
Did you get instructions for doing the update? It can take up to an hour, depending on your present software status and the number of upgrades that have already been done, if any.
I would recommend the dealer do the upgrade.
Are you sure it's the latest version disc?

On the off-road map and so forth, the MOST common cause for problems is the antenna. In the upper corner, when the car is outside and the NAV is on, are you getting the emblem that shows that you have locked on to satellites (looks like a ball with semi-circles underneath the ball), or you can also go into "service" and it'll actually tell you how many sat's you are receiving. I'd start there first. The only other thing I can think of is maybe you lost the info in COMAND on your tire size? This is critical that it's entered, if the info is gone it can really screw things up, especially if you experience long periods when you can't get satellites, like in tunnels or in parking ramps alot, things like that. In those times the COMAND requires accurate wheel speed info (including knowing the tire size) to do dead reckoning navigation.

Gilly

PS: No, the tape deck has no effect on the update, no relation at all.