The code for shift-keys, i.e. holding 1p start + something else is deceivingly complicated. It would be most interesting if you can provoke the same behaver with the 'USER-LOCK' switch enabled.So far I’ve experienced it on Progear, Donpachi and Dodonpachi. I’ll spend some time with different cores and see if it continues to happen. If it does I’ll edit this post to add it to the list or something.