I just replaced the mk III nav in my '01 740i with a mk IV (not sure what it came out of, got it on eBay). I got the latest (2006.2) blue dvd from a friend at a dealer and it works fine for the most part, but gets a little "lost". It thinks I'm about 1 street off from my real location most of the time. Any ideas? The mk III was dead-nuts accurate.