It is odd that the requests work in one type of browser but not another. Would you be able to post (or send to me in PM) the url of the site in question? I'd love to take a peek and see why this is happening.
Probably the easiest solution, assuming you are using the Apache web server, is to add the following lines to your .htaccess file:
Code:
RewriteEngine on
RewriteCond %{HTTP_HOST} !^www\.yourdomainhere\.com
RewriteRule ^/(.*) http://www.yourdomainhere.com/$1 [R=301,L]