r AdvamceMAME add in the in the file `advmame.rc' these options:
diplay_mode auto
display_adjust x
*... l clocks are supported by your monitor. Generally these values are specified in the technical page of your monitor manual. These are some example :
Generic PC SVGA multisync mon... horizontal frequency like 15 - 31 kHz. Generally these monitors support only the three fixed frequency 1