NMS studio will not open

Hi All, 

 We are currently facing a issue , NMS studio is not opening , opens up the login page and then it closes, 

checked the NMS studio logs 

ApplicationVersion=6.9.25399.0
OSVersion=Microsoft Windows NT 6.1.7601.65536
==========
IsTerminating=True
Source=mscorlib
Message=Exception has been thrown by the target of an invocation.
Exception=TargetInvocationException
StackTrace= at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at PtLaunch.PtLoader.RunApplication(ProductModule module, String methodName, Object parameter)
at PtLaunch.PtLoader.RunApplication(ProductModule module, Object parameter)
at PtLaunch.PtLaunchShell.RunViewer()
at PtLaunch.PtLaunchShell.Run(String[] args)
at PtLaunch.Program.Run(String[] args)
at PtLaunch.Program.Main(String[] args)
Source=PtPlatformClient
Message=Group node doesn't exist.
Exception=Exception
StackTrace= at PtPlatformClient.Reports.ReportViewerControl.LoadAvailableReportsList()
at PtPlatformClient.Reports.ReportViewerControl..ctor()
at PtPlatformClient.PlatformControl..ctor()
at PtPlatformClient.PlatformControl.get_Instance()
at PtPlatformClient.MainForm.LoadPerspectiveStudio()
at PtPlatformClient.PtViewer.Run(ClientConfiguration settings)
at PtPlatformClient.PtProgram.RunViewer(Object[] parameters

Kindly assist what can be done.

Regards

Sriram S