htaccess problem - no-www with pretty urls

[eddiegiese]

I'm trying to enable no-www in conjunction with taking a simple file (like /about.php) and rewriting it to /about/ but I keep getting a 406 error. Weird. Here's my code in the htaccess file. Any help is greatly appreciated as I've exhausted about 1000 different options.

RewriteEngine On
Options +FollowSymLinks
#
#Sub-dir
RewriteBase /
#
# no-www rewrite rule
RewriteCond %{HTTP_HOST} ^www\.example\.com$ [NC]
RewriteRule ^(.*)$ http://example.com/$1 [R=301]
#
# 301 Redirect all requests that don't contain a dot or trailing
# slash to include a trailing slash
RewriteCond %{REQUEST_URI} !/$
RewriteCond %{REQUEST_URI} !\.
RewriteRule ^(.*) %{REQUEST_URI}/ [R=301]
#
# Rewrites urls to be pretty but only rewrites
# if the requested URL is not a file or directory
RewriteCond %{SCRIPT_FILENAME} !-f
RewriteCond %{SCRIPT_FILENAME} !-d
RewriteRule ^about/?$ about.php [NC,L]
#
# Blocks image hotlinking
RewriteCond %{HTTP_REFERER} !^http://(www\.)?example\.com [NC]
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} ^http://.*$
RewriteRule \.(jpe?g|gif|bmp|png)$ - [F] 
#
# serve custom errors
ErrorDocument 404 /404.php