Hi, I have in the meantime determined that the problem only arises when attempting to use the numberpad. As long as I use on the left, standard mouse key and the numbers above the keys, everything is fine, but if I absentmindedly use the numberpad, I get a dropdown explaining that the right mouse key - which I didn't use - is deactivated and then the frozen window reacting to nothing and forcing me to use "force quit" = alt/Apple/esc. Bill