I'm experiencing this weird problem - doesn't matter what my front end is as I tried switching it.
As soon as I start pressing Player 1 Fire button (button 1, which translates to CTRL key in MAME config), I experience beeping sounds, coming out from the speaker, but after maybe a few key presses it goes away and all is good. Ie. So when loading up Galaga, whenever I press the fire button to shoot, I hear beeps drowning out the Galaga fire sound.
Anyone have any ideas what might be the issue?
Thanks.