Although this thread has been dead for a LONG time, I thought I’d add a post just in case someone was sitting in a similar situation to me.
I’m still using AE 7 on an Intel Mac Pro Dual Xeon 2.8 GHz Quads with 12 GB RAM (I know, why not just get a new AE when using this machine? Well…it’s coming soon). Anyway, I used to have occasional buffer issues, but recently, after upgrading to Snow Leopard, AE would hang on pretty much any render. Thankfully the workaround regarding dropping the memory down works FANTASTICALLY well!
I just thought I’d post and let anyone using an Intel Mac running Snow Leopard and AE 7 know that this works well. Thanks to Graham for originally figuring this out! You’ve saved me countless headaches!!!