I am having the same problem, after the latest SEO Plugin upgrade.
WordPress version: 3.4.1
WordPress SEO version: 18.104.22.168
I did this:
Within a new post page, I clicked on the arrow by WordPress SEO to add tags etc. Doesn't drop down. Also clicked on Add and Choose from most used tags under Post Tags. Neither does anything. Nor does Publish > SEO > Check link.
Also on the main All Posts page, when I click on Quick Edit next to any post, nothing happens.
I expected the plugin to do this:
I tried disabling WordPress SEO and aforementioned functions instantly worked.
My site: http://www.snlabetterway.com/news