the only .htaccess I have is the standard wordpress entries. I don’t think it is a rewrite problem.
Why are you so confident it is not a Download Manager problem? Any indications?
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>