Oh lovely.... QuickTime 7.4 totally ganked every machine in our studio that is running After Effects. It now craps out anywhere from 12-30 seconds worth of rendered frames and gives a nice, fat "After Effects error: opening movie - you do not have permission to open this file (-54)" error.".... now... we're pretty dang savvy at troubleshooting machines and have done all the usual (and unsual) fixes... nada. Nothing works. This is happening on all machines running After Effects CS3 8.0.1.... one 8-core machine is running 10.5.1 Leopard (yes, we know Leopard isn't fully AE compatible) and 3 separate machines (2 dual-core PPC and one 8-core Intel) running Tiger 10.4.11.... we have absolutely verified that it is the QuickTime 7.4 update causing this problem.