you are looking in the programs folder, not the users folder.
in the address bar enter:
this should bring you to:
c:/users/<your user name>/application data/
then look for adobe/Dreamweaver CS4/en_GB/configuration
if you are still having the same error, you most likely have an old extension version installed that is not compatible with DWCS4, send a screen shot showing the list of extensions and versions installed in the extension manager.