I’ve had a weird issue a couple of times on my work computer, where the keyboard and the mouse does not respond in Xorg after rebooting. As I only reboot my work computer every 80 days or so, I tend to forget the reason why it happens between each boot sequence.
The reason why the mouse and keyboard does not work after rebooting at my computer is that HAL or DBUS failed to start. I’ve not dug further into this issue, as it doesn’t happen very often. The solution:
(you can switch to a text console by pressing ctrl+alt+f1, your keyboard will work there)
Restart X / GDM:
Switch back to the Xorg terminal (alt+f7) and hopefully your keyboard and mouse will yet again work!