Ok, I've been struggling for weeks with my Topgun II's trying to get them to stop jumping around erratically.
I'm not sure what exactly fixed the problem, but here is what I did. I noticed that my mouse cursor was going completely off the right side of the screen, and then it hit me. Since the ArcadeVGA video card has 2 video ports, Windows XP allows you to use both ports for 2 monitors at once. So I am wondering if that might be screwing up the calibration, since technically the edge of the desktop that I had been shooting at, was only "half" of my desktop (sorry if that only makes sense to me). I went into the device manager and disabled the second VGA port, then restarted and the cursor now stays on the screen. Before all this I had also noticed that my monitor was not perfectly centered vertically/horizontally, so I opened up the cap and adjusted that with the knobs for the monitor. I also changed my resolution to 640X240.
I then tried to calibrate the guns and the very first try it worked absolutely PERFECT.
If any of you are having this same problem, please see if any of this helps you and let me know.