This is a pretty unique scenario, but if you are like me you’ve already been throwing stuff, smashing your mouse and pulling your hair out. And, that’s exactly why you found this on google. What was happening was, when I would try to use the spacebar and move a selection in photoshop the mouse cursor would move all over the place sporadically. I didn’t really notice it too much when I was in other applications because I would typically be typing with two hands and not moving the mouse.

So, if you started up bootcamp to run windows in fullscreen and then switched back to the mac side while it booted, it’s likely on another desktop asking you to log in. For some reason it doesn’t act like a second desktop until you are actually logged in to windows. When I switched over to windows from lion there was literally a paragraph of random letters in the password field and there were multiple pop-ups asking me to change my password.

This is the second time this has happened to me, so I’m assuming it has happened to someone else out there. I hope this helps you, if it does let me know.