404-errors with non-default permalinks

I have searched the internet and this forum, but I couln’t find the solution.

Suddenly, I get 404-errors with every permalink on my blog (https://cinemanimaniac.nl). I haven’t changed anything that could cause these errors.

When I change the permalinkssettings to Default, everything works fine. When I change back to Month and Name (/%year%/%monthnum%/%postname%/), I again get the errors, although the .htaccess file is nicely rewritten.

The home and wp-admin are working fine.

Current .htaccess:

# 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

WordPress 3.0.1.