Inexplicably mis-aligned photoshop layers
I have a rather odd problem with After Effects that I haven't found a solution for, so hopefully someone here can help me out.
I have created a 2D animated short film about half a year ago using photoshop layers as frames with the outlines, colour, shading etc. as separate layers on top of each other, all imported into and subsequently animated in After Effects without any problems.
Today upon opening the project file again for the first time since I see that all the individual layers in all compositions are now completely misaligned with each other in a rather chaotic manner. For some strange reason only background and outline layers seem completely unaffected by this.
I have changed neither the AE-file nor the Photoshop files since I've completed the film.
Here are screenshots of one shot- what it looks like now and what it looked like half a year ago

Here's a frame of character animation, same problem.
Mind you, the solid white character background doesn't stay consistently shifted to the left, it keeps jumping in all four directions in the following frames.

