You're selling a redirect rule...? RewriteEngine on RewriteCond %{HTTP_HOST} ^example\.com$ [NC] RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L]
You can't use a CNAME record for your root domain. This is a problem for me and lots of folks who run their web servers behind Amazon Elastic Load Balancers or other CNAME-based services. RootRedirect solves the problem nicely.