I recently rebuilt my Ubuntu machine (11.10) and since then I don't seem to be able to make Screen Sharing work.
Everything was fine before, but now when I try to share the machine's screen and Ubuntu is locked, I get a black screen that doesn't refresh. I've checked by watching the real screen and commands are getting sent. If I type the password and hit return then the machine logs in, but the screen share still doesn't refresh.
If I try to share the screen when Ubuntu is at the desktop, then it all works fine. It's something about the screen being locked that's borking it.