Comment 5 for bug 783439

Thanks. I was able to reproduce it in an almost fresh Natty 32bit install. It wouldn't hang right after the install, only after randomly installing and uninstalling presumably expendable stuff (e.g. mono). It may be a timing thing too, as it would still occasionally start into the unity desktop fine. Mostly it would get stuck at the empty wall paper as you described though.

There are some message in your and my .xsession-errors like

MaximizeIfBigEnough: Onboard window size doesn't fit

but poking that in the unity source didn't lead anywhere. I'm going to just let the unity devs have a look.