Thanks for your advice. I figured it was caused by the Fall 2011 Panda update. Some of the content on my site is almost 10 years old. Of course, I've added fresh content over the years, but I was one of the first airport shuttle directory/ reservation sites on the web. Other sites have plagiarized my text over the years. Can you offer anything specific I can do to recover from the Panda disaster? Do you think the new template will make a difference? The current site is built using Dreamweaver (lots of tables and cells... redundant code). The new template is very clean (built using CSS).
I'm thinking of changing the the names of my directories (e.g. a lot of my content is in the "airport_shuttles" directory). Would it help to create new directories? I've read that some SEO experts suggest completely rebuilding the site from the ground up is the only way to recover from the Panda update.