Logic Pro 7 & earlier Arrange track fracture Logic Pro 7.2.3

I often use cycle record, which has me either undoing the series via 'Undo' or manually rubberbanding the regions and deleting them. ( then often: 'delete unused tracks')

Every so often, I find that entire rows of regions have slipped up one space of my instrument list, and all the tracks are than played by the wrong instrument.

I haven't yet figured out how this happens, but it's a PITA.

Clearly I'm making a regular error but I haven't yet spotted what it is.

Can anyone help?