Yep.  Using the exact same settings I see the problem in 2.66 but not in 2.61. 

What's interesting is that, as you noted, with some degree of transparency enabled, the same "black box" appears every time the window resizes.  With no transparency it only happens when the window is initially resized the first time.  I have transparency turned off and fade into view turned on now, so I don't get the black box any longer.

Mouser, to answer your previous question, I did try v2.66 with a clean install + default settings and had the same issue. 

Thanks.  v2.61 doesn't have the problem.  

In v2.66.01, it happens when window is first displayed immediately before the last 9 results are displayed.  So, to answer your question, it's when displaying normal results.  It looks like the sequence of events is, 1-window is displayed, 2-window resizes (at which point the content area is black), 3-content area is rendered (with text, icons, and white background).  It happens very quickly, but the black to white change produces a noticeable "flickering" effect.  Hopefully that is helpful. 

One additional note.  After the initial results are displayed, it doesn't happen as the results change.