Comment 39 for bug 55172

@Achim: with mem=128M you can still log into the failsafe gnome session, it does not go to the full desktop :) Any value of mem in between should also work (like mem=256M). It is just used to create artificial slowdown so that starting of sudo gets slow.

BTW:
I got a user reporting that the hang is fixed for him with the new version of libgksu here:
https://bugs.edge.launchpad.net/ubuntu/+source/update-manager/+bug/253439/comments/9