If i switch DR one theres like a 33% chance that max crashes during the transforming vertices stage, without DR this doesn't happen. I don't understand why having DR on is causing this problem. It's not happened before and has been a recent thing with Corona 1.4 in heavy scenes using Forest Pack or vegetation models in general.
EDIT -In a bit of annoyance, i spammed the ESC key and it canceled the render and started to respond again, so thats good. but its still annoying that it happens.
some extra info for this, is that the render window displays everything at 99. so frame 99, time left 99:99:99. everything goes to 99 which is how I know its not going anywhere and crashed.