Mod Rewrite generating 500 internal error on page - apache

Question

For some reason my .HTACCESS file won't re-write my users page, even though I'm sure the code to re-write it is correct.
I want to turn
http://www.tfreeb.com/user/user?user=duenna
Into
http://www.tfreeb.com/user/duenna
And this is my HTACCESS file, could it be that something else is conflicting with it?
The re-write rule for the user page is right at the bottom.
Options -Indexes
php_flag display_startup_errors on
php_flag display_errors on
php_flag html_errors on
php_flag log_errors on
php_value error_log /home/path/public_html/domain/PHP_errors.log
php_value error_reporting 32767
ErrorDocument 404 /notfound.html
ErrorDocument 403 /403.html
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www.tfreeb.com$ [NC]
RewriteRule ^(.*)$ http://www.tfreeb.com/$1 [L,R=301]
RewriteCond %{HTTP_USER_AGENT} libwww-perl.*
RewriteRule .* – [F,L]
RewriteCond %{HTTP_HOST} ^213\.143\.20\.122
RewriteRule (.*) http://www.tfreeb.com/$1 [R=301,L]
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^\.]+)$ $1.php [NC,L]
RewriteEngine On
RewriteRule ^user/([^/]*)$ /user/user.php?user=$1 [L]

Answer 1

After:
RewriteRule (.*) http://www.tfreeb.com/$1 [R=301,L]
Try with that:
RewriteCond %{REQUEST_FILENAME} -d [OR]
RewriteCond %{REQUEST_FILENAME} -f
RewriteRule ^ - [L]
RewriteRule ^user/([^/]*)$ /user/user.php?user=$1 [NC,L]
RewriteRule ^([^.]+)$ $1.php [NC,L]
No need to use multiple times RewriteEngine On

Answer 2

Are you sure that the .htaccess is being read?
I'd try to make a basic redirect to some page, p.e. google.com if this doesn't work you should ask to the web server admin to give you the AllowOverride = all directive for the directory.
p.e.
<directory /var/www/mysite>
AllowOverride = all
</directory>