SQL prompt no longer works ...why?

I had sql prompt 2 for long time now and has been working flawlessly....until today...I get a SQL prompt error when I try to start it up...here is the error

************** Exception Text **************
System.TypeInitializationException: The type initializer for "_31" threw an exception. ---> System.Xml.XmlException: The root element is missing.
at System.Xml.XmlTextReader.Read()
at System.Xml.XPath.XPathDocument.Load(XmlReader reader)
at System.Xml.XPath.XPathDocument..ctor(XmlReader reader)
at RedGate.SQL.Shared.XMLSerializeFormatter.DeserializeRootObject(String fileName, String name, String typeName)
at _13._1()
at _31..cctor()
--- End of inner exception stack trace ---
at _40._40(Object , EventArgs )
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)


How can I resolve this? I try to unistall and re-install, I have also tried repairing the installation...nothing seems to work....