jar files

Hi, 

I downloaded DEMViewer jar files from the VISAD site using Netscape
Navigator (shift-click to save file), but unfortunately all of them cannot 
be unpacked properly under my windows environment. The error information is 
as follows:
-------------------------------
C:\visad\DEM>jar xf demv_src.jar
java.util.zip.ZipException: invalid entry size (expected 16896 but got 66
bytes)

        at java.util.zip.ZipInputStream.readEnd(ZipInputStream.java:350)
        at java.util.zip.ZipInputStream.read(ZipInputStream.java:140)
        at sun.tools.jar.Main.extractFile(Main.java:676)
        at sun.tools.jar.Main.extract(Main.java:639)
        at sun.tools.jar.Main.run(Main.java:190)
        at sun.tools.jar.Main.main(Main.java:778)
------------------------------

This is also the problem when I try to unpack other jar files downloaded
from the VISAD website. Can someone out there let me know the right way to 
download or unpack these files?

Thanks,

Bo Huang
Keele Univ., UK