i've been having this same problem .. although, it all works on one computer. i'm using the newest mameui64 emulator and on my current pc all the roms i have load just fine through launchbox - however, i downloaded launchbox on another pc, transferred my roms over and installed the same version of mameui64 and i keep getting this same error as above. mameui isn't the problem, launchbox is. i can load the games in mameui without an issue. i've imported my roms the exact same way i do on my other PC which works, but for some reason it's just not working on my other pc...
the only way i've gotten the roms to work is by putting them in mameui64's roms folder, then they'll load up from launchbox fine, but i don't have to do that on the other PC.. which i find strange.
any thoughts?