YIPEE!!! That fixed it - many thanks Megafiddle.

My test style dixiland.sty demonstrates the problem more than most and now it seems to be perfect if I set Slide Tracks to 1. So far I cannot find any disadvantages. I hadn't even realized this slide option existed,

It shouldn't really be necessary to use this workaround to get BIAB to stop this annoying behaviour. Surely some kind of permanent tiny delay can be built into the program.

I wonder if PG have tried to reproduce the problem in the way that I have suggested.

Thanks
Tony