Sounds like a corrupted memory problem to me, you could try an OS update and see if this fixeds the problem.

BTW the BT phonebook is held on the ULF not the mk4, if you are loosing this as well, then I think you may have a power problem in the boot of the car.

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Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.