I've been getting a bug in MameUI for a while now.
Whenever I run sfiii2n (Street Fighter III 2nd Impact: Giant Attack Asia NO CD) using widescreen mode from the Service Menu and quit, it seems to close MameUI64 but it's still open in the background and I have to close it using task manager.
Can anyone else reproduce this problem? It happens on two of my computers here. Windows 7 64-bit SP1, different hardware.