Jittery Image

[mamenewb100]

This is not a major issue but just a little annoying. I know it's probably normal to some extent to have "scanline jitter" because of the way a CRT projects an image. However on some games it is more noticeable than others. I'm using Makvision 2929D.

Could it be certain resolutions or frequencies that my monitor doesn't like? Or maybe vertical hold? Although I only see focus and brightness knobs on my monitor.  I notice it in Mortal Kombat especially in the top corners of the screen.