When I try to open or run .JNLP Files I always get a Unable to launch application error, I have JRE(Java Runtime Enviroment) 6 Update 6. I have tried many JRE Versions including JRE 6 10 Beta and still the same error pops up.
Heres what I get when it happens:

java.lang.NullPointerException
at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
at com.sun.javaws.Launcher.updateFinalLaunchDesc(Unknown Source)
at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
at com.sun.javaws.Launcher.launch(Unknown Source)
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

Java Web Start 1.6.0_10-beta
Using JRE version 1.6.0_10-beta Java HotSpot™ Client VM
User home directory = C:\Documents and Settings\MILTON
—————————————————-
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
—————————————————-
Running JVMParams: [JVMParameters: isSecure: true, args: -Xmx128m]
-> [JVMParameters: isSecure: true, args: -Xmx128m]
#### Java Web Start Error:
#### null

There was another Java application I tried, It was some kind of old Java web start Application. When I tried to open the JNLP file with that it happen to start downloading the JAR Files through it as it should but when it is near completion it pops up that it cannot run it and that it's apparently corrupted. I tried at least 7 times got the same thing. I've searched all over and can't find a solution to this problem and it is indeed annoying. I hope someone here can help me out.
Here is what I get when it says the file is corrupted:
An error occurred while launching/running the application.

Title: Pokemon Global
Vendor: Pokemon Global Team
Category: Download Error

Corrupted JAR file at http://pokeglobal.sourceforge.net/game/beta.jar


spec="1.0+"
codebase="http://pokeglobal.sourceforge.net/game"
href="beta.jnlp">

Pokemon Global
Pokemon Global Team
http://pokeglobal.net"/>
A Pokemon MMO.
A Pokemon MMO.





http://java.sun.com/products/autodl/j2se" version="1.5+" max-heap-size="128m"/>

http://slick.cokeandcode.com/demos/slick.jnlp" version="b231"/>










JNLPException[category: Download Error : Exception: java.util.zip.ZipException: error in opening zip file : LaunchDesc: null ]
at com.sun.javaws.cache.DownloadProtocol.doDownload(Unknown Source)
at com.sun.javaws.cache.DownloadProtocol.getResource(Unknown Source)
at com.sun.javaws.LaunchDownload.downloadJarFiles(Unknown Source)
at com.sun.javaws.LaunchDownload.downloadEagerorAll(Unknown Source)
at com.sun.javaws.Launcher.downloadResources(Unknown Source)
at com.sun.javaws.Launcher.handleApplicationDesc(Unknown Source)
at com.sun.javaws.Launcher.handleLaunchFile(Unknown Source)
at com.sun.javaws.Launcher.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

java.util.zip.ZipException: error in opening zip file
at java.util.zip.ZipFile.open(Native Method)
at java.util.zip.ZipFile.(Unknown Source)
at java.util.jar.JarFile.(Unknown Source)
at java.util.jar.JarFile.(Unknown Source)
at com.sun.javaws.cache.DownloadProtocol$RetrieveAction.actionDownload(Unknown Source)
at com.sun.javaws.cache.DownloadProtocol.doDownload(Unknown Source)
at com.sun.javaws.cache.DownloadProtocol.getResource(Unknown Source)
at com.sun.javaws.LaunchDownload.downloadJarFiles(Unknown Source)
at com.sun.javaws.LaunchDownload.downloadEagerorAll(Unknown Source)
at com.sun.javaws.Launcher.downloadResources(Unknown Source)
at com.sun.javaws.Launcher.handleApplicationDesc(Unknown Source)
at com.sun.javaws.Launcher.handleLaunchFile(Unknown Source)
at com.sun.javaws.Launcher.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)