Well, it is something to do with that particular track.
Other tracks in the project, all created with Step Sequencer, allow me to delete, no problem.
So grrrrrr to this track, but it is the only one I need to edit, and it would suck big time to have to re-enter these events. It is a drum track, from a Bill Bruford tune. It HURT the first time I entered the drums, going back a second time would make my head explode, like a penguin on the telly.
Bob Bone