Blender renders transparency as red? Animating a camera move that orbits around a central figure. The figure is backlit by a single light source behind it, but other than that, there are no backgrounds. Yet every time I render out (as a PNG sequence) I end up with a red background. Any idea what's causing this?

Here is the project file:
I am not sure if anyone is still looking for a solution to this, but the answer for me was to set the Alpha value in the material properties to Pre multiplied instead of Straight.