I am using MAMEUI32 v168, not PLUS or any frontends.
but looks like i have sorted it to some degree. I tried a different monitor and vga cable and received a different symptom. The screen went to a solid mixture of black and white when a game was started (solid in colour, ie no sign of the game that was playing), though I could still here the game.
What I've found is that direct3D is the problem the other video modes do not display the same as the original game and/or misbehave with lines rolling up the screen etc so I had skipped over them.
But....... "OpenGL" mode does not misbehave or have any distortions etc and looks close enough to the original game (for me).
Just out of interest though, can you tell me if the MAME Plus you mentioned is compatible with hiscore?