I notice you are still using Windows 7... I have been struggling to get Kega Fusion working properly in Windows 10... There surprisingly weren't many other alternatives available so I had no choice really but to get into Retroarch. I have gotten Retroarch working fine now and have grown to like it so I've pretty much moved on, but I really did love Kega Fusion when it used to work properly.
Specifically, I remember being unable to map controller inputs in Fusion for some reason (it would absolutely not detect controller inputs) so I had to map the controller to keyboard keys and then have Fusion interpret it as a keyboard inputs. I think I was running into some other issues that eventually made me give up but I forgot what they were now lol.