I think there are some issues with the javascript execution, on my PC and laptop anyway. When I have ad block disabled, I do not get the pop up windows when mousing over/clicking my inbox or alerts, or the user info window when clicking on someone's avatar. I just get the 3 bar animation in the top right corner cycling as if it's trying to load something, but can't.
As soon as a enable ad block, everything works as normal. Don't have this issue on the mobile site either.