I just tried it on Mame 0.174, and the same thing is happening.
I'm trying to narrow it down to the exact circumstances where this is occurring. It only seems to happen when I've got 1 player mapped to one X360 controller, and a second player mapped to another X360 controller. Then if I exit, unplug the second controller, and go back into Mame, it works fine. Until I hit Esc. That's when I get the error message and my controller configurations get reset.
This doesn't happen if I map player 1 to the X360 controller, and player 2 to my X-Arcade Tank Stick. If I unplug the Tank Stick and restart MAME, I can go into a game, play as one player, hit ESC, and nothing bad happens - I just get back into MAME.
So this seems weirdly specific to having two X360 controllers.
Edited by bacchuspup (05/29/16 09:06 AM)