Hi there. I'm having the same problem you describe -- only being able to fully boot using R&D mode -- on the N900, most likely for different reasons since I didn't have anything to do with Avahi.

Incidentally, the last things I did before rebooting were commenting out the fstab-gen lines of /etc/event.d/rcS-late and installing the fcam API package. I reverted those changes in R&D mode and tried reverting to production mode but no joy. I can't seem to narrow down the exact cause and am trying to remember all of the other changes I made since last boot...

Did you ever get to the bottom of your issue? Did you try uninstalling Avahi? If you learned anything else, maybe it can give me a clue. Thanks.