If "version" attribute is specified inside the jnlp file against the <jar> element then applet fails to load by throwing exception mentioned below. Applet works fine if no version is specified. Try loading following applets to reproduce the issue:

1) http://nicole1.sfbay.sun.com:8080/plugin_tests/JNLPSupport/jarCaching/html/TestMJ_ARJNLPVersionTest.html
2)
http://nicole1.sfbay.sun.com:8080/plugin_tests/JNLPSupport/jarCaching/html/TestMJ_ARJNLPVersionTest2.html

Exception getting Raised:
--------------------------
downloadVersion: 2.0, mimeType: application/x-java-jnlp-error)
com.sun.deploy.net.FailedDownloadException: Unable to load resource: (com.sun.deploy.net.FailedDownloadException: Unable to load resource: (http://nicole1.sfbay.sun.com:8080/plugin_tests/JNLPSupport/jarCaching/classes/b.jar?version-id=2.0, 2.0)
at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source)
at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
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.javaws.LaunchDownload.downloadJarFiles(Unknown Source)
at com.sun.javaws.LaunchDownload.downloadEagerorAll(Unknown Source)
at sun.plugin2.applet.JNLP2Manager.downloadResources(Unknown Source)
at sun.plugin2.applet.JNLP2Manager.prepareLaunchFile(Unknown Source)
at sun.plugin2.applet.JNLP2Manager.loadJarFiles(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by:
java.io.IOException: Error returned: 10 Could not locate resource
at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source)
at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
at com.sun.javaws.LaunchDownload.downloadJarFiles(Unknown Source)
at com.sun.javaws.LaunchDownload.downloadEagerorAll(Unknown Source)
at sun.plugin2.applet.JNLP2Manager.downloadResources(Unknown Source)
at sun.plugin2.applet.JNLP2Manager.prepareLaunchFile(Unknown Source)
at sun.plugin2.applet.JNLP2Manager.loadJarFiles(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)