Mouse cursor retreats to bottom left corner of screen and doesn't want to leave it

Every time I use Final Cut, my mouse cursor will sporadically shoot down to the lower left corner, and I can't move it for a few seconds - it just keeps shooting back down. It makes working really impossible.

I was running into this issue even while Final Cut was not open, and after taking my mac to the apple store and reinstalling my system, and no luck, I accidentally discovered that one of the default Mac screensavers, Drift, was causing the problem. Once I switched to another, it stopped.

But I've had no luck stopping the problem on Final Cut. Anyone?