Hi, I've had the same weird problem. IFOEdit seems sensitive to the order of user actions in author mode. Here's how it works for me: Choose the files (movie, sound, sup, celltimes, target) from top to bottom. After all the files have been set, change the language of the audio tracks and sups. Press <Tab> after you have chosen each language. If I change the language of the audio track before including the sup, I will get the error you described. Greetings, Dirk