avi,
What happens when you play the .AMV files downlaoded from our website? Try downloading some sample .AMV files on our website and see how they play.
If it doesn't jump, then it's the way you've encoded it, if it does, then it might actually be your player (I doubt it though).
Read the knowledge base here:
http://www.mympxplayer.com/viewtopic.php?t=32.
Step #6 mentions to encode the AMV with "HIGH" Frames per second and Image Quality. Did you that?