I noticed this problem running the SwingSet2 demo on Merlin b51 (actually
slightly pre-b51) on Solaris Sparc. After tooling around all over without
any problems, I glanced at my shell window and saw:

    java.lang.NoClassDefFoundError: java/util/Collections$SynchronizedList
            at java.util.Collections.synchronizedList(Collections.java:1706)
            at java.util.Vector.subList(Vector.java:971)
            at javax.swing.plaf.basic.BasicDirectoryModel$LoadFilesThread.run(Ba
sicDirectoryModel.java:324)

Unfortunately I don't know where in the demo I was at the time this
was generated, and I wasn't able to reproduce it.