I'm completely stumped!

I was using the airbrush tool like I always do in Photo Paint and all of a sudden my brush cursor began jumping up and to the left with each initial click, then drawing an unwanted line to where I was when I made the click. Now it's happening with airbrush, brush tool, clone tool, and every other tool that requires placement of the cursor.

I can't make it stop doing this, even with an F8 reset. Please tell me what I did to cause this and how I can make it stop...