Wow, without
Option "XkbModel" "microsoft"
it doesn't crash. My settings are now
Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "CoreKeyboard"
Option "XkbRules" "xorg"
# Option "XkbModel" "pc105"
# Option "XkbModel" "microsoft"
Option "XkbLayout" "de"
# Option "XkbVariant" "nodeadkeys"
EndSection