Lockup & other issues in MacOS 10.5.8

I’ve encountered three significant problems when testing UltraMixer Free on My MacBook Pro 17" 2.6GHz:

  1. When adding tracks to a playlist, either by drag & drop or by the “+ File” button, UM will frequently go into a ‘stammering’ slow playback mode - the current track continues to play in a broken-up fashion at about half speed, and UM hits 100% utilisation on one CPU. UM becomes completely unresponsive to controls, and I have to force-quit it & re-launch.
  2. When I delete a track from a playlist, it is no longer shown in the list, but something very strange happens when the playlist hits the point where the track used to be. Even though it is no longer in the playlist, the track appears briefly in the play window, and the progress bar shoots from left to right as if the track was being played at very high speed, then the next track plays normally. However, this leads to a couple of seconds of silence.
  3. If I re-order a playlist so that the next song scheduled to play is no longer the top of the list, it remains highlighted and will still be the next track to play. This means I cannot move another track to the top of the list and have it play next. Once a track is highlighted as being the active track, it will be played next regardless of what I do to the playlist order.