Is this a solution that is made up of more than one file? "This file" could be a different related file that has not been updated with your new account.
"Account cannot be used to access this file" does not sound like a standard error message, though maybe I just haven't encountered that one before. I think you'll need to open the script attached to the projects button in Manage Scripts and see what it does. It may be displaying a custom dialog with your error message and you'll need to find out what circumstances would cause it to do this.