After updating to the latest Java version on Mac OS X, I now get this exception when using JFreeChart:

Exception in thread "main" java.lang.NoClassDefFoundError: apple/laf/CoreUIControl

Not sure what the actual problem is, but at least one other developer has run into it:

http://discussions.apple.com/thread.jspa?threadID=2042441&tstart=0

The effect is similar to that described in this issue:

http://www.jfree.org/phpBB2/viewtopic.php?f=3&t=27783

This is almost certainly Apple's bug to fix, but maybe it is a good time to re-evaluate your reliance on UIManager to establish the default background color.  ;-)

G