So the multiple crashes start again.
Serves me right though, it was getting to be a pretty big file and I only had one copy (rookie error for an animation student I know, especially when working with the reliably unreliable Flash).
Tis fixed now, my scenes are now saved as separate files and I think I worked out that a symbol in one of the scenes was causing all the problems. Plus that scene had lots of tweens in, so Flash wasn't a particularly happy bunny, (ironically it's the scene in which my pet rabbits are, aharhar).
But it seems to be back on track! (Famous last words...) But at least since my RAM upgrade & shiny new external hardrive, my computer is being super quick at loading it up again, unlike the days of Formation, where it would take about 10 minutes to start up.
Hopefully I won't get a tally going again...