In AE CS3
My project contains several layers and also some pre-comped layers.
One of the pre-comped layers doesnt show up in the rendered file until about halfway into that comp. I checked everything I can think of. It looks fine while working in the project and it is fine in a RAM preview! It just disappears in the render.
Did you forget to extend the layer to the full length of its precomp?
Is it a 3D layer that's temporarily getting hidden behind another layer in 3D space?
Do you have OpenGL on and some kind of weird anomaly is happening?
Are you working with an interframe codec and some kind of weird anomaly is happening?