I'm not sure since which update the NextGen Gallery doesn't work with my WordPress installation. But it seems that the page, where you can upload images and add galleries and the options page of the nextgen gallery plugin doesn't show up anymore. So I'm not able to upload any new images or create new galleries. The old galleries work.
I already disabled contact form 7 since I read it could cause a problem. but it still doesn't work.
Does anybody know this problem and hopefully a solution to it?