Arcade ROMs won't run - "The operation could not be completed"

[punyweakling]

I'm running OpenEmu Experimental. Every Arcade ROM I try to run fails with a Generic error:

The operation could not be completed.
No other information is available about the problem.

[Click OK]

Couldn't communicate with a helper application.
Try your operation again. If that fails, quit and relaunch the application and try again.

Have tried 5 or 6 ROMs. Other cores (eg: SNES and SMS) seem to work fine.

Library path is set to ~/Documents/OpenEmu ROMs

Steps taken:

• Remove games from library (don't trash the games)
• Quit OpenEmu
• Relaunch
• Add games again
• Same error

Then:

• Repeat above steps with computer restart after removing games from library
• Same error

Then:

• Deleted OpenEmu.app
• Removed ~/library/app support/openemu
• Emptied trash
• Restart computer
• Download fresh version of OpenEmu
• Download fresh versions of Roms
• Add a new MAME ROM to the library and try to run it
• OpenEmu downloads and installs the MAME core
• Same error

Here's the console dump:

12/02/14 9:32:59.088 AM OpenEmuHelperApp[423]: parent application is: OpenEmu
12/02/14 9:32:59.130 AM OpenEmuHelperApp[423]: Some shit about the game.
12/02/14 9:32:59.140 AM OpenEmuHelperApp[423]: MAME: Audit failed with output:
gng         : gg-pal10l8.bin (44 bytes) - NOT FOUND
12/02/14 9:32:59.141 AM OpenEmuHelperApp[423]: ROM did not load.
12/02/14 9:32:59.141 AM OpenEmuHelperApp[423]: Deallocating proxy: <OEThreadProxy 0x7ff4e320c320, target: <MAMEGameCore: 0x7ff4e1c56c10>>
12/02/14 9:32:59.142 AM OpenEmu[324]: -[NSAlert alertWithError:] called with nil NSError. A generic error message will be displayed, but the user deserves better.
12/02/14 9:32:59.142 AM OpenEmu[324]: Warning: Exception caught during decoding of received reply to message 'loadROMAtPath:usingCorePluginAtPath:systemPluginPath:completionHandler:', dropping incoming message and calling failure block.

Exception: *** -[NSXPCConnection initWithListenerEndpoint:]: Endpoint argument is NULL.
12/02/14 9:32:59.145 AM OpenEmu[324]: Helper Connection (0x7fabb9d1ef40) failed with error: Error Domain=NSCocoaErrorDomain Code=4101 "Couldn’t communicate with a helper application."
12/02/14 9:34:16.197 AM OpenEmu[324]: Deallocating proxy: <OEThreadProxy 0x7fabb9883c80, target: <OEGameDocument 0x7fabb4c50ed0, ROM: 'gng', System: 'openemu.system.arcade', Core: 'org.openemu.MAME'>>

MacBook Pro (Retina, 15")
OS X 10.8.5
2.3GHz i7

Hopefully that's enough info to help trouble shoot?

Any help/advice would be amazing.

[punyweakling]

Is it possible ALL the ROMs I'm attempting to run are incomplete? (Trying to decipher the Console log).

[clobber]

Whatever you're trying to load requires additional files:

12/02/14 9:32:59.140 AM OpenEmuHelperApp[423]: MAME: Audit failed with output:
gng         : gg-pal10l8.bin (44 bytes) - NOT FOUND

Sounds like gng.zip