I just joined the forum to look into this problem. I've used Slice for a few years now and love it but just ran into this problem. I have a large file, a long audiobook, I like to slice into 5 minute segments so if I fall asleep or accidentally advance a track I don't have to FF through an hour long track (or in this case, the entire book). The file is an mp3 and I kept getting an error no matter what option for slicing I choose. I see the length shows a negative number though the properties of the file show the correct length. I re-encoded the file, even chose a lower bitrate to create a whole new file and smaller size but this new file does the same thing.