Not sure if this is a VAX or VS 2008 bug. The problem does not go away if VAX is disabled.
1) Attach the output pane to the bottom of the screen. 2) Open an html-file. 3) Select "Split" to view both the source and design. 4) Now close the output pane (and any other panes below the design view).
You will see the following:
What you see is the html window, an unpainted area (previously the design view) and the design view. The html window is not repainted until any of the windows are resized.