Comment 9 for bug 118593

todays my gutsy desktop start to have this behavior.
to solve:
launch gconf-editor from terminal
browse to desktop | gnome | peripherals | mouse
change mouse_acceleration properties.

i found the property just searching for "accel" also in key names.

just as a note, the problems arise seemingly from nothing, just yesterday the system updated gnome-tools to latest version from official repo.
At the same time, also the keyboard stop reapitin chars when a key is pressed. This problem still unsolved.
Gnome system menus icons also disappeared, still unsolved.