I love my rMB, but a single frustrating issue I have been having is erratic / jumpy cursor. For instance, I can be typing something in a window, and all of a sudden the position of the cursor jumps to a completely different part of the text.. or worse yet to a different window. This happens more often than not when I have a lot of windows open, but I have seen it happen even when the machine is fairly idle. This is hugely frustrating and has cost me a lot of lost productivity. I have owned plenty of MacBooks in my life, and have never experienced anything like this. Has anyone else with rMB been having this issue? Do people think I may have a unit with a defective trackpad?