Yep, thought as much... a load of our users have been logging in with a different case username than when they registered on our YaBB gold board
The convert app says this:
QuoteNote: On Windows-based hosts, usernames are case-insensitive. This may result in some posts being mislabeled as 'Guest' postings when in reality, a user simply posted while logged in with a different case (i.e. alexandra as opposed to Alexandra) for more details on this, and ways to get around the problem, please visit the YaBB SE Community
Umm... help?? any tools available to fix this please??