WordPress Installation after permalinks change not avaliable

Hello,

yesterday i set up an new wordpress installation on my new webspace (with mod_rewrite on).

I installed it, and the index.php works outside of the wordpress system directory.

After Installation, i changed the permalinks structure, and than, the page is not avaliable because it shows an 404 error.

I looked at the .htacess which is generated by wp:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

actually the index.php and the backend are not availiable only the 404 failures.

Anoyne here with an idea what the problem is? What should i do?