Phew okay. I gave this file one more go and it was definitely something up with the Lasso/Cutter tool cuz I managed to save the file this time. I wanted to copy over a portion of a drawing onto a later frame to save time but each time I tried, the software would lag very badly. Even after Stamping, erasing the portion that was stamped and redrawing it didnt help the situation either; the file continued to crash during Saving.
So this time I abandoned the Lasso/Cutter use and just drew what I needed and Saved. This time it worked which is… nice but not really the end-goal for that tool, even if its selecting multiple drawing strokes. That said, I saved the file as a different filename (which did nothing to help last time around). Im over the hurdle but I can send over the file that was giving me trouble if you wish, Niel.