I haven't seen a mention of this in the forums so I didn't know if this is a known problem.
There's a UI display problem when editing an HTML file caused by the VA X. The problem occurs when you're in HTML mode (as opposed to Design). Normally, while in HTML edit mode, there is a tool bar under the edit window with two buttons: HTML and Design. When VA X is enabled, you can't see the buttons, instead you see remnants of the whatever happens to be in that area when you gave focus to Visual Studio. Moreover, you can't interact with the buttons to force a refresh. I'm using the 1237 build but this problem was seen long before this build -- I had hope someone would have caught it so it saves me from posting. This problem only occur when "View Context and Definition fields" is set to bottom of source window which might account for why it was missed.