It appears that the jar files referenced in http://dl.javafx.com/1.3/javafx-rt.jnlp are no longer available. To reproduce the problem you can remove one of the required runtime jar files from the cache.

We have customers reporting this issue on OSX after a recent Java update (which we believe is clearing the cached runtime files). Here's the stack trace we see on OSX clients:

com.sun.deploy.net.FailedDownloadException: Unable to load resource: http://dl.javafx.com/1.3/javafx-rt-macosx-universal__V1.3.1_b101.jar
at com.sun.deploy.net.DownloadEngine.actionDownload(DownloadEngine.java:1416)
at com.sun.deploy.net.DownloadEngine.getCacheEntry(DownloadEngine.java:1569)
at com.sun.deploy.net.DownloadEngine.getCacheEntry(DownloadEngine.java:1547)
at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(DownloadEngine.java:1654)
at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(DownloadEngine.java:1578)
at com.sun.deploy.net.DownloadEngine.getResource(DownloadEngine.java:215)
at com.sun.javaws.LaunchDownload$DownloadTask.call(LaunchDownload.java:1983)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:680)