At some point, which I can't describe with more details, keynav will cause the keyboard to freeze with the error Unexpected X11 event: 65. I have to kill keynav (by jumping in an old-school TTY terminal) in order to get the control of the keyboard back. Once it happens a first time, there's nothing to do. Every time keynav will be restarted and triggered by the appropriate keystroke, the same thing will happen. There nothing to do other than restarting X in order to "fix it" for a while. I don't know how to reproduce for now.