Hello,
 i run the installer from Windows XP Home Edition Console (cmd.exe) with Java version 1.6.0_16:

> java -jar jython_installer-2.5.1rc2.jar

then, the 'Jython Installation' window appears but, when i try to 'click' on any command i get:

Exception in thread "AWT-EventQueue-0" java.lang.ClassFormatError: Unknown constant tag 0 in class file javax/swing/JInternalFrame
    at javax.swing.plaf.basic.BasicLookAndFeel$AWTEventHelper.eventDispatched(Unknown Source)
    at java.awt.Toolkit$SelectiveAWTEventListener.eventDispatched(Unknown Source)
    at java.awt.Toolkit$ToolkitEventMulticaster.eventDispatched(Unknown Source)
    at java.awt.Toolkit.notifyAWTEventListeners(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)
Exception in thread "AWT-EventQueue-0" java.lang.ClassFormatError: javax/swing/JInternalFrame
    at javax.swing.plaf.basic.BasicLookAndFeel$AWTEventHelper.eventDispatched(Unknown Source)
    at java.awt.Toolkit$SelectiveAWTEventListener.eventDispatched(Unknown Source)
    at java.awt.Toolkit$ToolkitEventMulticaster.eventDispatched(Unknown Source)
    at java.awt.Toolkit.notifyAWTEventListeners(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)
Exception in thread "AWT-EventQueue-0" java.lang.ClassFormatError: javax/swing/JInternalFrame
    at javax.swing.plaf.basic.BasicLookAndFeel$AWTEventHelper.eventDispatched(Unknown Source)
    at java.awt.Toolkit$SelectiveAWTEventListener.eventDispatched(Unknown Source)
    at java.awt.Toolkit$ToolkitEventMulticaster.eventDispatched(Unknown Source)
    at java.awt.Toolkit.notifyAWTEventListeners(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)


while, the GUI does nothing.

Thanks.