I've got this problem where my cursor is jumping left and right all on it's own. I'm not touching the computer at all, I've rebooted the system, and the only way to get it to stop is to use a mouse and disable the trackpad when a mouse is connected.
Here is a video showing the problem
http://www.youtube.com/watch?v=IXUGwhv7h8I
Seems I had damp fingers when using the trackpad. Caused the sporadic issues for about 3 days. Then it all went away.
Unexpected input when the trackpad is enabled? Unfortunately, it seems like physical damage to me. Aside from giving the trackpad a rigorous cleaning, I don't think there's much that can be done without voiding your warranty. I'd recommend taking it into an Apple store and getting it checked out by a hardware tech.
