It's tough to come up with a summary for this one.

Basically, I have a Supermicro system with an embedded WPCM450 management controller that provides KVM over IP via a java application deployed with a JNLP file.  I believe Dell is using the same management controller in their newer products.

You click on a button, the browser gets a JNLP file and asks what to do with it.  Rawhide offers to open in IcedTea webstart, which starts up NetX, downloads various jars and aborts with:

net.sourceforge.jnlp.LaunchException: Fatal: Launch Error: Could not launch JNLP file.
        at net.sourceforge.jnlp.Launcher.launchApplication(Launcher.java:372)
        at net.sourceforge.jnlp.Launcher$TgThread.run(Launcher.java:600)
Caused by: java.util.zip.ZipException: error in opening zip file
        at java.util.zip.ZipFile.open(Native Method)
        at java.util.zip.ZipFile.<init>(ZipFile.java:131)
        at java.util.jar.JarFile.<init>(JarFile.java:150)
        at java.util.jar.JarFile.<init>(JarFile.java:114)
        at net.sourceforge.jnlp.Launcher.launchApplication(Launcher.java:345)
        ... 1 more
Caused by:
java.util.zip.ZipException: error in opening zip file
        at java.util.zip.ZipFile.open(Native Method)
        at java.util.zip.ZipFile.<init>(ZipFile.java:131)
        at java.util.jar.JarFile.<init>(JarFile.java:150)
        at java.util.jar.JarFile.<init>(JarFile.java:114)
        at net.sourceforge.jnlp.Launcher.launchApplication(Launcher.java:345)
        at net.sourceforge.jnlp.Launcher$TgThread.run(Launcher.java:600)

However, I can't figure out which zip file is problematic, or what is supposedly wrong with it.  The files look OK to me when I download them manually and unzip them.  I also tried with F10 but the behavior is unchanged, so this doesn't seem to be a regression.

I can verify that Sun java seems to have no problem opening these files.

Unfortunately I'm not sure what information I can supply.  I saved the JNLP file and the jars it references in http://www.math.uh.edu/~tibbs/java-problem.  I can put the management console of one of these systems on the public Internet and provide a login if someone's interested in debugging it that way.

Just doing some more debugging, I see that netx seems to have created a file JViewer.jar.info in /tmp/cache containing:

#automatically generated - do not edit
#Fri May 22 11:06:19 CDT 2009
last-modified=0
content-length=-1
last-updated=1243008379527

I can't see that it actually downloaded any of the jars, however.