This is a good news/bad news post. The good news is that the upgrade to Bb 9.0 SP4 is finished a bit early and you can go back to getting your courses ready for the fall semester.
The bad news is that in some browsers, you get a white screen when clicking on a test or quiz to take it (see the picture below). This has been reported to Blackboard and we're looking forward to a fix as soon as possible. Right now quizzes are working as expected in Firefox 3.6.6 and IE 7. The browsers known to have problems are IE 8, Safari 5.0.1, and Firefox 3.6.8.
I'll post an update as soon as we find out any more information about this.