I want to include a level in my game with a variety of moving blocks, and I've got it working 99%, except that they sometimes just stop while moving and then start up again as if nothing happened, but then they get out of sync. I have an example here with the mouse position being used to trigger the blocks. Notice how they occasionally stutter or just suddenly stop while moving, when they shouldn't. Any idea what I did wrong?

blockproblem.mfa