Dragging User Controls in HTML View
Oh good lord. You drag in an ASCX file to an ASPX page while looking at the page in HTML view. The code generated is a hyperlink. People! You know you can't link to an ASCX file, and that if you do you'll get an error anyway. How did this slip through code review or user-acceptance testing?!?!?!? Did no one actually write any HTML by hand? WTF?