I am currently using Sag Timeslips 2013 and every time we go to generate a bill, we get an error message stating "An error occurred while retrieving data from a list structure in memory. Since the list structures are used in all aspects of this program, the cause is unclear. Note the actions that lead to this. List class: tCoverPageTokenListC. I have tried changing the navigator from enhanced to classic, I have checked the database for errors, cleared all search defaults and I have tried uninstalling and reinstalling and I still get the same error. Any help would be highly appreciated.