[chrishajer]

Is it possible the files were corrupted upon uploading? Seems like it’s a server configuration thing, not even related to PHP or CGI. You should be able to view this file, for example, but you cannot:

http://www.kreativoase.at/taufkerze/forum/bb-images/bbpress.png

In fact, it’s an internal server error code 500, but the server is configured to show this error message, which might be misleading. If you have access to error logs, that will help determine what’s causing the 500 error.

If it’s something applying to that directory and all lower lever directories, maybe there is a problem with the .htaccess file (if you are using one) in the forum directory. Do you have a proper .htaccess file? Please post the content here. I am starting to think an error in the .htaccess file is the problem for it to cause a 500 error on the forum directory or any subdirectory you try to access.

Permalinks on false is good.

bbPress does not need its own database, but it does need a database, and the table prefix will be bb_ by default. So long as that doesn’t conflict with any other tables you already have, it’s OK to use an existing database.