ClassCastException EndpointStrategyConfigImpl

Hi,
We have installed SOAPUI 3.0.1 and SOAPUI 3.5 on a couple machines, it works on some and on others we get the following in the soupui-errors.log

2010-07-20 10:09:01,769 ERROR [errorlog] java.lang.ClassCastException: com.eviware.soapui.config.impl.EndpointStrategyConfigImpl cannot be cast to com.eviware.soapui.config.DefaultEndpointStrategyConfig
java.lang.ClassCastException: com.eviware.soapui.config.impl.EndpointStrategyConfigImpl cannot be cast to com.eviware.soapui.config.DefaultEndpointStrategyConfig
at com.eviware.soapui.impl.wsdl.endpoint.DefaultEndpointStrategy.initConfig(DefaultEndpointStrategy.java:93)
at com.eviware.soapui.impl.wsdl.endpoint.DefaultEndpointStrategy.init(DefaultEndpointStrategy.java:66)
at com.eviware.soapui.impl.wsdl.WsdlProject.<init>(WsdlProject.java:267)
at com.eviware.soapui.impl.wsdl.WsdlProject.<init>(WsdlProject.java:178)
at com.eviware.soapui.impl.wsdl.WsdlProjectFactory.createNew(WsdlProjectFactory.java:51)
at com.eviware.soapui.impl.wsdl.WsdlProjectFactory.createNew(WsdlProjectFactory.java:24)
at com.eviware.soapui.impl.WorkspaceImpl.createProject(WorkspaceImpl.java:436)
at com.eviware.soapui.impl.actions.NewWsdlProjectAction.perform(NewWsdlProjectAction.java:116)
at com.eviware.soapui.impl.actions.NewWsdlProjectAction.perform(NewWsdlProjectAction.java:51)
at com.eviware.soapui.support.action.swing.SwingActionDelegate.actionPerformed(SwingActionDelegate.java:101)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.AbstractButton.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(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.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)
2010-07-20 10:09:01,785 ERROR [errorlog] java.lang.NullPointerException
java.lang.NullPointerException
at java.util.Hashtable.put(Unknown Source)
at javax.swing.JEditorPane.registerEditorKitForContentType(Unknown Source)
at javax.swing.JEditorPane.registerEditorKitForContentType(Unknown Source)
at javax.swing.JEditorPane.loadDefaultKitsIfNecessary(Unknown Source)
at javax.swing.JEditorPane.getKitTypeRegistry(Unknown Source)
at javax.swing.JEditorPane.createEditorKitForContentType(Unknown Source)
at javax.swing.JEditorPane.getEditorKitForContentType(Unknown Source)
at javax.swing.JEditorPane.setContentType(Unknown Source)
at javax.swing.JEditorPane.<init>(Unknown Source)
at com.eviware.x.impl.swing.SwingDialogs.showExtendedInfo(SwingDialogs.java:138)
at com.eviware.x.impl.swing.SwingDialogs.showExtendedInfo(SwingDialogs.java:124)
at com.eviware.soapui.support.UISupport.showErrorMessage(UISupport.java:621)
at com.eviware.soapui.impl.actions.NewWsdlProjectAction.perform(NewWsdlProjectAction.java:165)
at com.eviware.soapui.impl.actions.NewWsdlProjectAction.perform(NewWsdlProjectAction.java:51)
at com.eviware.soapui.support.action.swing.SwingActionDelegate.actionPerformed(SwingActionDelegate.java:101)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.AbstractButton.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(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.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)

Does anyone have an idea what the problem could be?
Thanks,
WwH