Never heard this before mate, reload an OEM v32 and see if the "fixes" the problem.

The only other thing I can think of is the battery was on its way out and turning on the lights causes a massive power drain and reboots the nav.

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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.