How do I deactivate links and form elements in flash in a bottom layer when I have a layer on top?

When you say "layer" i assume you mean a flash layer, not a css layer.

An easy way to do this is to put an invisible button on top. Just create a button, dont put anything into the first three frames, just define the hit area in the last one. You can show it when you want to deactivate the layers below it, and hide it when you want to reactivate them.

Thanks Dascope