Check The Foundry's website for the latest updates of Keylight. Most likely it's sucking up all your resources. I'm sure the footage will render perfectly without it, so the logical conclusion would be to get a decent keyer like Primatte on of these days... ;-) If it still hangs, then lower the number of processes to use for rendering. Quite possible, that actually renders go to fast (in terms of processing) and your file I/O can't keep up. Lastly, try different CoDecs and formats. Some of them are simply not MP safe and cause trouble...
Thanks for your help. I've tried a variety of processor to RAM setting combinations with no luck so far, so your suggestion about Keylight is something I completely overlooked. Do you have a preference of keying software? Sounds like you prefer Primatte, which I've never used before, I will Google it and see what I come back with.
I have no preference in keying, but Keylight hasn't really seen much development over the years and now looks a bit dated. And as hinted, over the years some ugly bugs have crept up which lead to excessive memory consumption and a number of other minor oddities. There's always the chance it could be responsible. anyway, use whatever you have or can afford.
I've got this same problem on my machine. 8-core (16 threads) 2.26GHz and 12GB RAM.
It seems to be happening during a CC-sphere effect section of the animation.
Did you find any solutions in the end?
Thanks for the link, that's interesting.
I don't think that's the issue with mine though. If I run in single core mode each frame in the animation takes 1.5 minutes... so maybe it's just a huge render and thus the activity monitor thinks it's not responding. It does slowly do the job though it seems.
If I use all the cores all my RAM dissapears, thus causing even more problems.
I've also tried just using four cores giving them 2GB each, but the same thing happens.
Thanks for the reply though.