As I click Calculate Motion Study, the part (or sub-assembly) moves as it is supposed to, but in the end when it should stop (sometimes during the move also), it jumps instead, to a random position linear to the movement direction. The end key also turns red, and with more complicated motions, some bits of the timeline turns red.

The problem is with one particular assembli, and also with all the older versions of it. And there was no problem when I started animating, a few days in, it just stopped working properly.

I'm using Solid Works 2008 and Assembly Motion.

I have tryed making the assembly smaller, by deleting over 500 parts. Tryed deleting all the mates for the part. I also tryed deleting Windows "temp" folder. I even tryed reinstalling SW and using another computer. Nothin'

Here's an example of the result

Thank you for your time