Yay. I fixed my problem...
Some time ago (and I can't exactly remember why), I created a symbolic link for a tools.jar in my Java 6 installation. E.g.:
/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/lib/ tools.jar -> /System/Library/Frameworks/JavaVM.framework/Versions/ 1.6.0/Classes/classes.jar
If I rename/delete "tools.jar", then my build problem goes away. --kevan
