ZC Version: 2.53.1 Beta 40 Build 33
I think I had this problem with Beta 36 as well (sorry for not mentioning before). So, when I try to reassign the game buttons to different keys on my keyboard, this error shows up; even if I press "OK" and leave everything as it is. I found that the culprit is assigning the "B Button" to the "left control" key. Assigning it to any other key is fine.
It might not be a critical bug, but it is annoying considering I used the B button on the left control key. In case of need of further details, I'm running ZC on Windows 10.