Explorer 9 Flicker on hover

Your's works fine on IE9.

Mine won't work with either the protostar or Beez3 templates.

I haven't tried reinstalling since it was working on other browsers. Should I try that?

try the maximenu theme css3megamenu and see if you have the same problem
I have no idea for now about the issue you have.

That works. I created my own template so maybe I stuffed something up there - I will leave your css3megamenu up for now to keep the wolves at bay and redo the custom template on the development site. Thanks