Java SE (Java Platform, Standard Edition)

I am JNLP & JavaFX newbee. I have deployed and launched application successfully via web [jnlp]. I used FX ant tasks to build the deploy and used the html fragment generated to run the application within the web browser [IE8]. [Added fragment to jsp]. The web application is using Spring MVC and Spring security. When I open the javaws viewer, and try to start the application, it doesn't start and I see this error [assuming it is root cause]:
...
basic: Relaunch because: [current UI toolkit does not match]
Exception in thread "thread applet-com.xxxxx.aops.javafx.app.AopsApp-1" java.lang.NullPointerException
at com.sun.deploy.cache.Cache.getCacheEntry(Unknown Source)
at com.sun.deploy.cache.Cache.getCacheEntry(Unknown Source)
at sun.plugin2.applet.viewer.JNLP2Viewer$1$3.appletJRERelaunch(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.fireAppletJRERelaunch(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
...

Not sure what the NPE is all about, but assume it is related to the "current UI toolkit does not match". I am using jdk/jre 1.7.07 javafx 2.2

Thanks,
David