Peter Kes

You need to make sure that the display_types are defined in Nextgen/your_WP_database

Try this:
https://your_site/wp-admin/edit.php?post_type=display_type

If you don’t get the 7 NextGen types displayed (e.g. NextGEN Basic SinglePic), your DB is corrupt for as far as Nextgen is concerned.

See if you can find a backup to restore the post_type=display_type posts.

There is a way to create these manually in phpMyAdmin, but it is not a pretty process.

I have the same type of behaviour here.
With a post containing:

[singlepic id=abc]
[include-page id=xyz]

the singlepic shortcodes in the post don’t resolve.
The singlepics in the included page do resolve.

If I remove the include-page tag, the singlepics of the main post are resolved again.

Going back to NextGen 1.9.13 did it for me.

Update: I had Firefox 3.6 installed (on Mac). Downgrading to Firefox 3.5.7 fixed the problem.