Just installed the KQ4-6 pack today. I had the graphics problems with the goofy colors so I changed the graphic mode to "overlay" as suggested here in the forums. Problem solved.

HOWEVER, KQ6 is having a strange problem where the opening scenes and I assume cutscenes as well, have a jerky/flashy artifacting going on with every movement. It look like it could be a video buffering issue.

I'm running on W7x64. Any suggestions?

Sounds like GOG version has the same bugged graphic driver as the 2006 King's Quest collection had. Only way to fix that is to replace the file with file from another Sierra's early VGA SCI adventure game.

The problem only affects to opening, rest of the cutscenes should work just fine, because those don't use the same engine as the intro movie.