The Original Poster stated that the error message was a missing traffic.DLL - NOT the default traffic file which is a BGL.
The Traffic.dll resides in your modules folder (or is supposed to).
The file in question can be restored from the install disks.
The resources will be helpful in that reagrd:
http://www.cat-tamer.com/flightsim/faq001.htmlIt shows where everything is on your install disks and how extract just what you need.
I also recommend fs9cddir.zip Compiled by Brian Collins.