I've had a couple of sudden crashes with 2.1.5.1250 — no error message, no prompt to send a report to Maxthon on startup (although my most recent changes seem to be preserved, and max:last opens up fine on startup).
Best I can remember these have been on sites where I moused over Flash elements — but I can't make it recur by revisiting the sites afterward.
It's happened on different PCs running the same (synched) copy of Maxthon. They could just be flukes, but I thought I'd ask if anyone else has noticed anything similar.