I don't think we know a single solution.
See this thread:
The link I refer to in post 1 (that refers to removing previous authorscriptsessions) is not relevant to CS6 - where they appear to automatically remove the old sessions.
If you will go back to http://forums.adobe.com/community/encore and enter
in the area just under Ask a Question
You may now read all the previous discussions of your error... be sure to click the See More Results at the bottom of the initial, short list if the initial list does not answer your question