Do this instead:
Options +FollowSymLinks
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.EXAMPLE\.TLD[NC]
RewriteRule ^(.*)$ http://EXAMPLE.TLD/$1 [L,R=301,NC]
# Send request via index.php
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L]
</IfModule>
<FilesMatch "\.(ttf|ttc|otf|eot|woff|font.css|css)$">
Header set Access-Control-Allow-Origin "*"
</FilesMatch>
Change EXAMPLE and TLD to your domain name.
Also check the domlogs to see what's actually wrong. The logs will say which line is giving error 500:
tail -f /usr/local/apache/domlogs/YourDomain