When attempting to open Creative Cloud Lightroom 5 for the first time, a popup dialogue box reads: "An error occurred when attempting to change modules." I am unable to switch between catalogs, import photos, or anything else. I followed the guidelines on this page (http://helpx.adobe.com/lightroom/kb/error-changing-modules-lightroom.html), and was unsuccessful in solving the issue.
Same problem for me. I did every step of the guideline but nothing.