I've got unzip 5.32 on my machine, and when I run it against the class file, it gives me a reasonable listing. Perhaps you have a bad class file? Somehow corrupted in the download? I've put a gzipped version of my good jython-21.class in ftp://ftp.parc.xerox.com/transient/janssen/jython-21.class.gz for you to try if you'd like.
Bill
