I was recently assisting a client who was receiving TSCAL (licensing) errors when logging into 2008 terminal server via a Wyse thin client.  After researching found that it was caused by the default User not having write access to the registry that is needed to be able to re-write the hardware ID under MS licensing.  Here is how I was able to fix the problem: [more]

  1. Login as Administrator locally in to the device and disable the write filter
  2. Launch the registry editor and navigate in to Hkey_local_machine\Software\Microsoft\
  3. Select MSLicensing > right click select Permission  > Click on Advance tab
  4. Set the User  and the Power User  to have full control