I just did a clean install of joomla 3.1.1 and MC. I noticed there is no description on permissions page in the MC options. It just lists a bunch of radio buttons to choose from, but does not say what they are for.

I have included a screenshot.




Also I noticed that after a new install of MC it gives text that says to go into Options and save it. If one clicks on the text link in that message it opens up the options in a full page, instead of under the admin headers. That way there is no menu or buttons, which makes it hard to save without a save button. If they click on the options icon instead, then it works just fine. You might want to update the text link so that it functions like the options icon button.