Updated the software today, it took the update fine from the BMW CD. But no luck in fixing the issue. I still get the "PLEASE WAIT ..." note when I try to access the GPS navigation mode. This is now intermittent with an error stating that the CD/DVD is unreadable.

I am thinking that the next step is most likely to replace the navigation disc. I am checking eBay and finding that there are quite a few CD's/DVD's out there. Which is the best upgrade for a MKIV?