Comment 6 for bug 237604

I've been having this problem across several versions of Ubuntu, and have been affected by the problem both in KDE and Gnome.

One link that has been suggested is that it could be related to some keycode-related error messages that keep appearing in dmesg :

[quote][4335062.871000] atkbd.c: Use 'setkeycodes e02a <keycode>' to make it known.
[4335063.546000] atkbd.c: Unknown key pressed (translated set 2, code 0xaa on isa0060/serio0).
[4335063.546000] atkbd.c: Use 'setkeycodes e02a <keycode>' to make it known.
[4335063.607000] atkbd.c: Unknown key released (translated set 2, code 0xaa on isa0060/serio0).
[4335063.607000] atkbd.c: Use 'setkeycodes e02a <keycode>' to make it known.
[4335073.996000] atkbd.c: Unknown key pressed (translated set 2, code 0xaa on isa0060/serio0).
[4335073.996000] atkbd.c: Use 'setkeycodes e02a <keycode>' to make it known.
[4335074.114000] atkbd.c: Unknown key released (translated set 2, code 0xaa on isa0060/serio0).
[4335074.114000] atkbd.c: Use 'setkeycodes e02a <keycode>' to make it known.[/quote]

These error messages can be stopped by going to System->Administration->Services and disabling a service known as hotkeys-setup.

In yet another attempt to make Ubuntu usable again I've disabled this service, so if the system remains functional, expect to hear more from me.