Customer reported the following behaviour, that I was able to
 confirm experimentally on Windows XP SP2 and a slow ethernet 
 connection (e.g. 1 MBps DSL line) using their application.

 The customer's Web Start application depends on Windows using
 native libraries. It depends on JRE 1.4.2_12 as Java runtime.

 When loading customer's Web Start application over a slow connection
 on Windows it sometimes spontaneously fails to load when using Java 
 Web Start 6. It then issues the following error message in a simple 
 message box with an OK button:

    Failed to Start application 'e-FX Dealer LIVE Client'
    null Unable to call main(...) function on class
    com.barcap.fox.commondeliveryplatform.DefaultFoxSystem!
    OK

 Trying to rerun without clearing the cache leads to the following
 Web Start error:

   Application Error: Unable to launch the application

   java.lang.UnsatisfiedLinkError: no WinInfo in java.library.path 


 Java Console shows

Java Web Start 1.6.0_03
Using JRE version 1.4.2_15 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\Administrator
----------------------------------------------------
c:   clear console window
f:   finalize objects on finalization queue
g:   garbage collect
h:   display this help message
m:   print memory usage
o:   trigger logging
p:   reload proxy configuration
q:   hide console
r:   reload policy configuration
s:   dump system and deployment properties
t:   dump thread list
v:   dump thread stack
0-5: set trace level to <n>
----------------------------------------------------
BS_VERSION = 1.0.9.2
Check sum == 1575237221
java.lang.UnsatisfiedLinkError: no WinInfo in java.library.path
    at java.lang.ClassLoader.loadLibrary(Unknown Source)
    at java.lang.Runtime.loadLibrary0(Unknown Source)
    at java.lang.System.loadLibrary(Unknown Source)
    at com.barcap.fox.bootstrap.app.ReadWinInformation.<clinit>(Unknown Source)
    at com.barcap.fox.bootstrap.app.Main.isOffLine(Unknown Source)
    at com.barcap.fox.bootstrap.app.Main.main(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.sun.javaws.Launcher.executeApplication(Unknown Source)
    at com.sun.javaws.Launcher.executeMainClass(Unknown Source)
    at com.sun.javaws.Launcher.doLaunchApp(Unknown Source)
    at com.sun.javaws.Launcher.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
#### Java Web Start Error:
#### null

 Exception tab shows:

java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.sun.javaws.Launcher.executeApplication(Unknown Source)
    at com.sun.javaws.Launcher.executeMainClass(Unknown Source)
    at com.sun.javaws.Launcher.doLaunchApp(Unknown Source)
    at com.sun.javaws.Launcher.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.UnsatisfiedLinkError: no WinInfo in java.library.path
    at java.lang.ClassLoader.loadLibrary(Unknown Source)
    at java.lang.Runtime.loadLibrary0(Unknown Source)
    at java.lang.System.loadLibrary(Unknown Source)
    at com.barcap.fox.bootstrap.app.ReadWinInformation.<clinit>(Unknown Source)
    at com.barcap.fox.bootstrap.app.Main.isOffLine(Unknown Source)
    at com.barcap.fox.bootstrap.app.Main.main(Unknown Source)
    ... 9 more

 After clearing the Web Start 6 cache regarding the application a 
 retry usually works fine to start the application.
 The problem was never observed for Java Web Start 1.4.2 or 1.5.