IE Stylesheets being ignored - only on production server though
IE chokes if you have more than 31 stylesheets, which most Drupal sites do if you create a zen subtheme. Turn on CSS aggregation in your performance settings to fix that.

There are potential (temporary or easily fixable) problems associated with migrating a Drupal site from http://example.com/dev/ to http://example2.com/ that you can avoid completely if you develop on a subdomain, ie. moving http://dev.example.com to http://example.com

check your database and theme files for paths starting with "dev/" and give your .htaccess files the once-over.