I'm really confused by this. So: The keys U, I and O are working BUT only under two circumstances.
A: When I press one of those 3 keys really quick after pressing for example the key "A"
B: When logging in or typing my password when "sudo-ing" something.
I just don't get it and I don't know at all how to fix it.
EDIT: Only the lowercase U, I and O aren't working. But when holding shift they work. On the other hand, activating Caps Lock doesn't bring them back to life
EDIT 2: I'm using a german keyboard and in Xubuntu im using the "Generic PC-Keyboard with 105 Keys" layout. Also please consider that I'm a beginner in Linux :)