Design Tab shows Black screen, nothing happens

Hello,
I am new to vaadin, I tried using vaadin with eclipse, it worked fine intially, but it generated a popup saying I need to install XULRunner, which I did succesfully (since I do not get the pop up)
what happened is after Installing XULRunner and providing access, through specified command, I was not able to open the DESIGN tab associated with the UI class,nothing happens when I switch from source to design tab, it just remains on source and if I minimize and remaximize Eclipse it just shows a complete black screen, I tried creating a new Vaadin 7 project and running the design tab on it, same issue, I DO NOT get any ERROR MESSAGE, it just displays a black screen. I have taken all the basic steps(re-instaling latest eclipse plugin, restarting laptop, restarting eclipse)
Also I tried finding the threads relating to the issue I have and wasnt able, so I posted a new thread.
I have created Vaadin composite, and since I have tried opening design Tab in new Vaadin 7 project, I can assure that I have not edited anything in @AutoGenrated Module.
Thank you in advance.
OS-Windows 7(64 bit)
IDE-Eclipse JUNO
Plugin- Whatever Latest Eclipse market provides.