vaadin client side error

Hi ,
I tried to start my vaadin( 7.5.6 ) application by using maven archetype

vaadin-archetype-application-example,

Code compiled and tried to run spring tc server. But I getting some client side error that unable to trace through even debug window. I extracted some part of large client side strack trace. Hope someone have any clue about this. Please help me.

Thanks
Chatura

SEVERE: Error sending hierarchy change eventscom.google.gwt.event.shared.UmbrellaException: Exception caught: (TypeError) : Cannot read property 'getParent__Lcom_google_gwt_user_client_ui_Widget_2' of undefined