Java Launch fails on second run: java.lang.NullPointerException

Programmer Question

I downloaded the .jnlp file and ran it. It runs fine. I close it and start it again, it runs fine.

However on the third try, it always throws java.lang.NullPointerException and the application will not launch.

If I restart the computer it works again. How can I fix this ?

java.lang.NullPointerException
    at com.sun.javaws.security.SigningInfo.overlapSigners(Unknown Source)
    at com.sun.javaws.security.SigningInfo.getCertificates(Unknown Source)
    at com.sun.javaws.LaunchDownload.checkSignedResourcesHelper(Unknown Source)
    at com.sun.javaws.LaunchDownload.checkSignedResources(Unknown Source)
    at com.sun.javaws.Launcher.prepareResources(Unknown Source)
    at com.sun.javaws.Launcher.prepareAllResources(Unknown Source)
    at com.sun.javaws.Launcher.prepareToLaunch(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)

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