какая версия ubuntu ?
для 8.04 (Runtu 3)
sudo gedit /etc/X11/xorg.conf
Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "us,ru"
Option "XkbVariant" ",winkeys"
Option "XkbOptions" "grp:ctrl_shift_toggle,grp_led:scroll"
EndSection