The developers usually want to see your debug.err file (found in your Documents\MyGames\LegendaryHeroes folder) for these types of problems so that they can see your graphics hardware and software. Can you post that here?
Also, they'll often ask if your graphics drivers are up to date, so that's something you can check on.
You might also check your LH options and turn down the antialiasing if you have it enabled.