I have a 3 minute video that i'm trying to render to external HD as QT with Animation codec. Yet the render keeps quiting on me after about 80% finished. I know i have enough space on the HD... So what can be the problem???
Does it keep showing the rendering dialog but the CPU is at nearly 0%? How much memory is used for the render? Check the task during a render (i.e. not too far from the point where it fails). Check both the RAM used and the virtual memory used (you may have to turn on the VM column in the task manager).
If the total (RAM + VM) approaches 2GB, that's going to stop it.