Hey, thanks for your reply!
You are right, I am using Unibios. It is actually happening with console mode "Arcade". That issue is not there with my other games, so I guess it's not related to hardware switch settings, I will check it nevertheless. And if I set the console mode to AES, I am sadly not getting PRESS D FOR OPTIONS. But no problem, I will survive it :-) Thanks for your hard work!!! We love it!