Comment 346 for bug 353126

https://bugzilla.redhat.com/show_bug.cgi?id=214446 seems to be a duplicate of this bug. Ubuntu launchpad says the bug is in xorg or possibly the ATI/nvidia drivers: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/353126

For a workaround in your shell type:
gconftool-2 -s -t bool /desktop/gnome/remote_access/disable_xdamage true