I'm fairly certain this has been discussed before but I can't seem to find the relevant thread. My 15" tMBP seems to not display buttons from time to time. For example, at this moment, I can't see the Esc key, nor any of the "system" buttons (brightness, etc). If I tap where they're supposed to be, they show up and function normally, but by default, they're not displaying. Has anyone found a solution or cause for this? Doing something like activating the screensaver seems to fix it, but only for a short period of time. Thanks!