VMM = Virtual memory (As in, it uses a cache partion on the hard drive that act's like ram but isn't as fast as real ram.) Force VMM = the vm.txt is not used and you have to manually set the parameters for each game. So, Press start - at the main Mamedox screen. Press A over - "Options Menu" Press L or R Trigger - Till you find "Force VMM?" Press A - Till the right column says "No" Press Start - To exit Now Mamedox will use the VM.txt. witch has predefined Parameters for optimal use. If they still don't work you may have to run them/ROMS through Romcenter and hunt for missing files. Peace