It has been different things each time, when I recieve the Error. The only way I have been able to fix the problem ( for a short period of time at least ) has been to delete all of the files on the server, and re-upload them all and redo the install (ie. running the /calander/setup/index.php file). Each time the Error first occurs after I have done different things. One time it was while trying to access the User Manager, another time it was while trying to access the Event Manager, another time it was while trying to access the Database setup. Once the error appears, I am completely locked out of everything and can not even run the demo.php, or the /setup/index.php. At that point I am forced to delete all of the server files under the calander directory and re-upload everything.
I was thinking that it might be something the the PHPSession, but even after completely closing my browser and deleting cookies, etc. I remain locked out. So, I started thinking it might be something to do with the License.