The D Codes table uses a third part OCX control called pvdt70.ocx.
It is installed in the Windows System32 folder (C:\Windows\System32).
It neeeds to be present and registered. If registration has failed the D Codes table will not work.
To fix:
(1) Remove and reinstall the software. On Windows 7 or Vista make sure that you run the installation while logged in as an administrator
or
(2) Open a command prompt in the folder C:\Windows\System32 while logged in as an administrator (Win7 or Vista run the prompt "As an administrator") then type:
regsvr32 pvdt70.ocx
You should see a confirmation dialog pop up if the operation succeeded.