Log a bug against the Runtime => http://javafx-jira.kenai.com
There was a somewhat similar issue with Ensemble earlier (also a signed embedded app)
http://javafx-jira.kenai.com/browse/RT-26971"Sample Showcase (Ensemble) does not start"
Ensemble also wasn't starting due to access permissions on a property lookup. It was an issue with a different property though as ensemble's encountered the error trying to access "java.net.useSystemProxies".
I'm sure what was done to fix Ensemble as I don't have access to the patch link.
Finally, the system seems to consider my applet as unsigned... but I don't know why, I use the javafx Ant task...
I've used an old trick: System.setSecurityManager(null); just before JAXBContext.newInstance(NEEDED_CLASSES);
Probably not the best and clean way, but pretty darn effective.
The main problem for me is the opacity of this new version.
How to anticipate next JRE version?
How to use this technology in a professional environment if each JRE update can break my application?
The biggest problem is the integration in the browsers.
The behavior is not the same according to the browser. Chrome seems to be more cool. Firefox don't like java plugin...
Today, I'm really not sure to have choosen the best technology and I'll probably evaluate flex/flash.