Meanwhile I found that the Ctrl-Alt-Fn problem is a known issue (see https://bugs.launchpad.net/ubuntu/+source/usplash/+bug/447692), so it probably is not related to this problem.
Meanwhile I found that the Ctrl-Alt-Fn problem is a known issue (see https:/ /bugs.launchpad .net/ubuntu/ +source/ usplash/ +bug/447692), so it probably is not related to this problem.