Whenever i zoom in on something or right click to use my camera on Myst IV there is cursor lag. I tried setting my settings to windows xp service pack 2 and that helped most of the lag, but there is still some lag keeping me from solving that pesky snake puzzle!
You might have to find a saved game from after the snake puzzle. There are saves for Myst IV at http://www.nicouzouf.com/en/?page=list&alpha=m but they don't seem to be individually labelled.