Opening pre-comp everything works fine, but in the composition the animation is reversed...

[ekurtis]

Hopefully you can see that in one of these images the arms look "normal" and in the other they are reversed. What did I do??

[ekurtis]

The problem is now in both comps. The arm pieces randomly switch positions to their reverse.

[Duduf]

I don't understand what your problem is from the images. Can you be a bit more specific about how your project is set up, or maybe post a screen shot or a video recording of what's going on in After Effects?