I just installed NextGen and as soon as it is activated, the whole Website causes a 500 server error.
The integrated test for plugins/theme conflicts fails to run (even after disabeling all other plugins and switching to twentyten) but the other two tests show that the plugin should work.
I got different adresses for the Website and the wordpress installation (http://www.stereoreklame.de and http://www.stereoreklame.de/wordpress) so I wonder if it may cause trouble with the default gallery folder...
would be great if anyone knows how to fix this.