Se me olvidó un breakline:
Código Apache:
Ver original<IfModule mod_rewrite.c>
Options +FollowSymLinks
RewriteEngine on
RewriteBase /
RewriteCond %{SCRIPT_FILENAME} !-d
RewriteCond %{SCRIPT_FILENAME} !-f
RewriteRule ^(.*)$ $1.(htm|html|php)
</IfModule>