Ghost box covering controls

I've got a GVH 2.3 viewer with a "ghost" box (in the form of an empty box with a white outline) floating above the base maps drop down and toolbar tab. I have no idea where it came from but I can't click on the toolbar tab or base map drop down till it's gone. Any thoughts?

/customer/servlet/servlet.FileDownload?file=00P6000000elzP2EAI