It's jerky!!!!

[-=Drifter=-]

I started working on this pic today and all of a sudden things are jerky as can be. Nothing is accurate anymore. I can't even draw a line and have it go where I want it to - it's offset for some reason.
Opening any other drawing of mine and playing with them - they are smooth as silk.
I cleaned the registry, defragged my memory, cleaned all caches, ETC., and even completely shut down the computer and turned it back on after a few minutes --- and that file is STILL acting really weird.
PLEASE tell me it's not corrupt and I lost the whole thing - the back up file is the same way.

Here's the file - I am drawing the stereo camera that goes with the stereo viewer I drew earlier.