I have a 2010 whit MB that has Mavericks running on it. Occasionally it dies something where every app open will slide to the left just about 1/4th inch but the menu bar stays normal. I try to move the open window to its normal position but then the tight side falls off the dark space on the right as if that's the edge of the screen. I had to take a picture with my iPhone because screen cap won't work during this and many apps freeze also. Even the desktop itself is slid over that much and only rebooting fixes it till next time.