first of all my WordPress installation is in a subfolder and everything worked perfectly, but now I wanted to directly link from my homepage to my wordpress blog.
I copied the index.html and .htaccess from the wordpress folder and pasted them in to my root folder. Then I edited the index.html to require the wp-blog-header.php with the correct path (/wordpress/wp-blog....)
The redirecting works perfect, but now my NextGen Gallery is broken. Attach to post just shows me a blank page and attached galleries are not displayed. Also my Lightbox wasn't working.
First I tried to correct the Lightbox paths in Other Options. I tested the corrected paths, but my lightbox was still not working. So I resetted NextGen. Now Lightbox is working again, but attach to post and attached galleries are still not working.
I also tried deactivation other plugins, but there was no change.