Hi There,
Thanks for writing in and sorry that you are running into some issues with the Keyword Difficulty tool. Unfortunately, Google has changed the way that they present rankings information, so we have had to make some changes to our collection in order to keep up with these changes, I'm afraid that this has caused some issues with providing the real time data for the Keyword Difficulty tool and the tool is currently unresponsive. We are hopeful to have the tool working again within the week, but at this time, unfortunately, we do not have an exact ETA for when that tool will be up and running again. I thank you for your patience while we work to resolve this issue.
We will be posting updates on this issue in our Known Issues forum when they become available. You can access that forum here: https://seomoz.zendesk.com/entries/22457872-keyword-difficulty-and-rank-tracker-issues
I apologize for any inconvenience this may cause.
-Chiaryn