Apache2 causing infinite redirect loop when forcing www

Apache2 causing infinite redirect loop when forcing www

I'm trying to force users on my site to use the www version, however my
configuration is causing an infinite redirect loop. The relevant
configuration is below:
<VirtualHost *:80>
ServerName www.mydomain.com
DirectoryIndex index.html index.php
DocumentRoot /home/me/sites/mydomain.com/htdocs
# Log file locations
LogLevel warn
ErrorLog /home/me/sites/mydomain.com/logs/error.log
CustomLog /home/me/sites/mydomain.com/logs/access.log combined
</VirtualHost>
<VirtualHost *:80>
ServerName mydomain.com
RedirectMatch permanent ^/(.*) http://www.mydomain.com/$1
</VirtualHost>
This method is the way I've found to be the most acceptable from answers
on Stack Overflow.
However, when browsing to www.mydomain.com or mydomain.com the following
happens:
http://i.imgur.com/1dcEY5x.png
As you can see, it's bouncing me between www and non-www until the browser
quits.
I've verified that it's not a .htaccess issue by completely removing it
from my document root, yet it still happens.
Any ideas?