Ok,

1: you have downloaded v29.1 and unzipped it.
2: you have loaded the .iso file into a iso reader (like UltraIso) and drag n droped the navboot file out to the Desktop.
3: modded navboot with navteak (then saved).
4: drag n dropped navboot back into the iso (using UltraIso).
5: saved the modded iso image
6: used imgburn to write the now modded iamge to the disc.

Sounds like the iso write image is not working properly, you are not unzipping the .iso to the hard disc then writing the unzipped (and unpacked) iso to a blank cd are you??

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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.