Well, I think we have identified the link/unlink issue.
@mrpacdan,
The first thing I would do is begin checking each of your plugins to ensure they are rated up to WordPress 3.6. If it is not, I would recommend finding a replacement that is.
Do this for all plugins except NextGen. Leave that one deactivated until the very end of this process.
Once you have activated all of your other plugins (except NextGen)… are you still experiencing the site issues?
@seamoose37,
I’m really at a loss here. I am totally unfamiliar with NextGen and have never used it on any of my websites. I only found the above fix by digging into their code. Since multiple people are reporting this as ‘fixed’, I really don’t know what’s going on in your environment.
Try deactivated ALL of your plugins… then manually refresh the browser cache… and see if that allows you to link/unlink.
That way, we can rule out your theme and the WP core files.