Javascript error - msddSettings is undefined

I have tried both the 7.x-1.5 and 7.x-2.5 versions, and neither is working for me. The language switcher appears, but when you pull it down, nothing happens. The language doesn't switch.

Firebug is telling me that msddSettings is undefined in lang_dropdown.js, on line 10, the problem is with flags = msddSettings.languageicons.

I'm not using language icons.

I only get the js error when I am logged out. But it doesn't work logged in or out.

I have tried different language detection options. That does not seem to be the issue.

Can anyone point me in the right direction? I've tried different versions of jQuery. Is there a likely module conflict or something else I can try?

Thanks!