So if you have modules with buttons try to disable them for that page. (on our site it was "Wetter Online")
I hope that's the cause on your site too.
@Moderators: Because it's about EL could you move this topic to that area please?
Hm, don't know if CB modules could conflict, have no site with EL and CB together. For test you could disable them.
If I remember right I used browser's developer tools / firebug to set a break at next scrpt call and clicked on Save. Then I was surprised on which script the briowser stoped but got the corresponding module.
Not sure if this is the right way but it's the only problem I know for that use-case.