@mrrhq, Welcome to TMO! Although I get the impression that you more-or-less know what you're doing, I would advise you to treat extras-devel with EXTREME care. This is not Debian. Packages in extras-devel are in development, and anyone can upload anything that "upgrades" (read: fvks up) critical system packages in the worst imaginable ways. Normally you enable extras-devel to install a single package, and then disable it. NEVER do apt-get upgrade with extras-devel enabled. NEVER do apt-get dist-upgrade under any circumstances (extras-devel or not). I repeat: this is not Debian! Enjoy your N900!
You might have walked into the trap some guy created with his upload of libxau6 package. (snip)
NEVER do apt-get dist-upgrade under any circumstances