The "Custom Main Menu" feature is the one that causes problems with Bluetooth (not the Video Playback or MP3 features). None of the 34xx devices support the Custom Main Menu in their firmware and so there is no sense in enabeling it at all. I did quite a bit of testing with all of the various features in my 3760 to 3490 conversion, and the Custom Main Menu is the only feature that caused me any grief at all.