Keyboard sticks randomly

Solution 1:

Since there are now two related posts on this I'm guessing it's a bug. A simple workaround would be to turn off repeated key presses.

1. Click the icon at the very right of the top panel and select System Settings.
2. In the Hardware section, click Keyboard.
3. On the General tab, turn off Key presses repeat when key is held down to disable repeated keys entirely. Alternatively, adjust the Delay slider to control how long you have to hold a key down to begin repeating it, and adjust the Speed slider to control how quickly key presses repeat.

(via Official Ubuntu Help Documentation.)