I have my wordpress installed…

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http://en.support.wordpress.com/com-vs-org/

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But now I want to change the wordpress- and site address in the general settings to the shorter url, which is causing troubles.
I first only changed the site address, because the other one can be the longer one. If I then go to: http://domain.nl/wp.domain.nl/sample-page/ it shows the error page instead of the page I want to see when I have the longer url filled in.

The htaccess I use for the main domain is:
php_value upload_max_filesize 20M<br /> php_value post_max_size 20M<br /> php_value max_execution_time 200<br /> php_value max_input_time 200</p> <p>AddHandler application/x-httpd-php .gif .jpg .jpeg .png<br /> php_flag short_open_tag Off<br /> php_flag display_errors off</p> <p>RewriteEngine on<br /> Options +FollowSymlinks<br /> RewriteBase /</p> <p># REDIRECT MAIN DOMAIN<br /> RewriteCond %{HTTP_HOST} ^(www.)?domain.nl$<br /> # /subfolder/<br /> RewriteCond %{REQUEST_URI} !^/www.domain.nl/<br /> # Don't change this line.<br /> RewriteCond %{REQUEST_FILENAME} !-f<br /> RewriteCond %{REQUEST_FILENAME} !-d<br /> # /subfolder/<br /> RewriteRule ^(.*)$ /www.domain.nl/$1<br /> # site<br /> # subfolder/<br /> RewriteCond %{HTTP_HOST} ^(www.)?domain.nl$<br /> RewriteRule ^(/)?$ www.domain.nl/ [L]</p> <p># SUBDOMAINS to /sub.domain.nl/<br /> RewriteCond %{HTTP_HOST} ^([^.]+)\.domain\.nl$ [NC]<br /> RewriteCond %{HTTP_HOST} !^www\.domain\.nl$ [NC]<br /> RewriteRule ^(.*)$ http://domain.nl/%1.domain.nl/$1 [P,L]

This should do the following:
http://www.domain.nl -> http://www.domain.nl/www.domain.nl
sub.domain.nl -> http://www.domain.nl/sub.domain.nl