IIS7 ObjectDisposedException WindowsIdentity

Hi there, I am trying to move a working application from IIS 6 to IIS7 integrated mode but I'm running into a bit of a problem that I cannot solve. My app is based on windowsauthentication and I use this throughout my app. In the app itself I'm using a self defined prinicpal that inherits from WindowsPrincipal like so: MyWindowsPrincipal : WindowsPrincipal MyWindowsPrincipal(WindowsIdentity Id) :base(Id) {} Now when I run this app in classic mode all is fine however when I switch to Integrated mode things go downhill. I have a masterpage that tries to go into HttpContext.Current.User to obtain the users name. This fails with the following error: Safe handle has been closed Source = mscorlib, Type = System.ObjectDisposedException, Time = 1-4-2011 19:18:12 StackTrace of the exception = at System.Runtime.InteropServices.SafeHandle.DangerousAddRef(Boolean& success) at Microsoft.Win32.Win32Native.GetTokenInformation(SafeTokenHandle Token ...