Okay, I recently discovered an issue with my dock. Every now and then, it will disappear and begin acting as if the option to hide until mouseover is enabled. It still works, but hides itself automatically. I think the issue is related to Movist/fullscreen movies somehow, because the dock disappears when the movie is in full screen mode. For some reason, it stays that way afterwards. To fix it, I have to tick/untick the dock option to hide automatically. It's incredibly annoying. Anyone have a fix?