Think I have found it, the session data is getting lost for some reason. Going to try and use the 'remember' information. Problem is that it can't be relied on as it is optional.
Will have to try the right way, if that fails try the remember if that fails then they need to visit the forum then back to Q2A, could I make a suggestion you have the same error description in all of the files, it would help if which file is emitting the error was discernible.