Running Mavericks 10.9.5, every time I reboot I get a prompt to login to iCloud. Whether I enter the correct password or garbage the prompt window reappears until I cancel it twice. iCloud sync with Calendar and Contacts work perfectly. AppleCare's answer is to upgrade to Yosemite -- which I would do only after cloning the hard drive and testing every application (e.g., a pain). Could this be an application causing the prompt, and how would I find out which one needed an application-specific password?
thanks