This is now a discontinued product and Trailer Life/Undertow don't provide assistance and support.
From their official website:
"Please note that the Trailer Life Navigator product has been discontinued by Trailer Life and so has the Agreement between Undertow Software and Trailer Life. Undertow Software is no longer providing support for this product. You can contact Trailer Life with any questions you may have about it."
However, you can read about general questions through the following link: http://undertowsoftware.com/support/tldcn2010.htm