a couple of things to check, first is that your JAVA version is 1.7, type java -version in command prompt to confirm. Make sure you have uninstalled the previous Schedule Connect and installed the newly downloaded one from 13.3.
This error can also be caused by a time out. Check the global session timeout set in CSA, and the minutes of inactivity unit logout from the administration system options page, typical length for the system option I believe is 60 minutes