java.lang.NullPointerException
   at org.mozilla.browser.MozillaExecutor.asyncExec(MozillaExecutor.java:342)
   at org.mozilla.browser.MozillaExecutor.mozAsyncExec(MozillaExecutor.java:508)
   at org.netbeans.core.browser.xulrunner.BrowserPanel.requestFocusInBrowser(BrowserPanel.java:250)
   at org.netbeans.core.browser.xulrunner.WebBrowserImpl$BrowserContainer$1.run(WebBrowserImpl.java:540)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:137)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)