My University uses the Blackboard Learning System - I don't know who supplies it or anything like that. The display from this system no longer renders properly in either Safari 4 (DP), or the Nightly build of WebKit. It renders properly in Firefox. As soon as I resize the window, the display fixes itself up. There are some images in a post at: http://schinckel.net/2008/06/11/blackboard-learning-system-and-safari/ Something with WebKit/Safari 4 seems to be screwing with other applications: ecto is eating posts, and WordPress won't let me edit any more, but I haven't quite hunted that one quite as much. I've put it into the Java Component, since BLS is a Java application, I think. It might be a frames issue, as resizing the window fixes up the frame rendering.
<rdar://problem/5999633>
Could you please attach a web archive of a relevant page? (Without too much personal info, hopefully). It's difficult to diagnose exactly where the issue lies from a screen shot alone, as there's many possible DOM trees (and CSS/JS files) to create a given look.
The web archive does not show any problem for me, and does not look anything like the screenshots shown at the aforementioned http://schinckel.net/2008/06/11/blackboard-learning-system-and-safari/