Poor response

My 4.1.1 musescore periodically seizes and there is no response. I have subsequently changed computers to get more threads, cores, memory, faster SSD and moved my scores from Google Drive to my local storage. This has improved the situation somewhat but musescore still hangs for no apparent reason. It collects my keystrokes and applies them in random fashion to adding accidentals, note input - whatever. My versions also does crazy things with selecting single or multiple measures. The outline will appear as a thin box on top of the measures or extend from top to bottom on the score. The display is crazy but underneath, the software 'does the right thing' with the measures.