A client called me today, because some of his galleries weren't working.
I recently upgraded him to latest version of nextgen.
Two most recent galleries ("2013" and "2104" are working) The older ones simply go to the home page when clicking on them.
When I mouse over the newest galleries the path displayed is:
http://www.xxxxx.com/picture-galleries/nggallery/picture-gallery/"name of gallery"]/
When I mouse over the older galleries it simply shows a pointer to
http://www.xxxxx.com (where xxxxx is his domain.)
I checked the galleries - all the paths in the "manage galleries" say: wp-content/gallery/[name of gallery]
The "Page link to" all say "not linked"
I made sure the permalinks are all month and date.
I have deactivated every plugin except Nextgen.
Can't see any difference in the two kinds of galleries.
Even went so far as to make sure the album is "not linked" to any page.