java.lang.NullPointerException
        at javax.swing.JSplitPane.setUIProperty(JSplitPane.java:1057)
        at javax.swing.LookAndFeel.installProperty(LookAndFeel.java:262)
        at javax.swing.plaf.basic.BasicSplitPaneUI.installDefaults(BasicSplitPaneUI.java:333)
        at org.openide.explorer.propertysheet.PropUtils$CleanSplitPaneUI.installDefaults(PropUtils.java:1707)
        at javax.swing.plaf.basic.BasicSplitPaneUI.installUI(BasicSplitPaneUI.java:301)
        at javax.swing.JComponent.setUI(JComponent.java:673)
        at javax.swing.JSplitPane.setUI(JSplitPane.java:355)
        at org.openide.explorer.propertysheet.PSheet.createSplitPane(PSheet.java:701)
        at org.openide.explorer.propertysheet.PSheet.addImpl(PSheet.java:550)
        at org.openide.explorer.propertysheet.PSheet.setState(PSheet.java:401)
        at org.openide.explorer.propertysheet.PropertySheet.setDescriptionAreaVisible(PropertySheet.java:392)
        at org.openide.explorer.propertysheet.PropertySheet.setDescriptionVisible(PropertySheet.java:399)
        at org.openide.explorer.propertysheet.PropertySheet.init(PropertySheet.java:342)
        at org.openide.explorer.propertysheet.PropertySheet.<init>(PropertySheet.java:249)
        at org.netbeans.core.NbSheet.<init>(NbSheet.java:118)
        at org.netbeans.core.NbSheet.getDefault(NbSheet.java:190)
        at org.netbeans.core.NbSheet$Replacer.readResolve(NbSheet.java:434)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:0)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at java.io.ObjectStreamClass.invokeReadResolve(ObjectStreamClass.java:1061)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1762)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351)
        at org.netbeans.modules.settings.convertors.XMLSettingsSupport$SettingsRecognizer.readSerial(XMLSettingsSupport.java:542)
        at org.netbeans.modules.settings.convertors.XMLSettingsSupport$SettingsRecognizer.instanceCreate(XMLSettingsSupport.java:574)
        at org.netbeans.modules.settings.convertors.SerialDataConvertor$SettingsInstance.instanceCreate(SerialDataConvertor.java:415)
        at org.netbeans.core.windows.persistence.PersistenceManager.getTopComponentPersistentForID(PersistenceManager.java:513)
        at org.netbeans.core.windows.persistence.PersistenceManager.getTopComponentForID(PersistenceManager.java:618)
        at org.netbeans.core.windows.PersistenceHandler.getTopComponentForID(PersistenceHandler.java:422)
        at org.netbeans.core.windows.PersistenceHandler.load(PersistenceHandler.java:147)
        at org.netbeans.core.windows.WindowSystemImpl.load(WindowSystemImpl.java:69)
        at org.netbeans.core.NonGui$3.run(NonGui.java:205)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)