Sorry if this is a known issue but i wasn't sure what to search for. My 13" 2011 MacBook Pro every so often locks up when i try to wake it from sleep mode. Sometimes the screen is just black but the keyboard is illuminated in which case i can close and re-open the laptop and it works fine. Other times the screen looks like this (see attachment) and there's no way of making it usable again without a hard reset (pressing the power button for a few seconds). Any advice? I know i should probably call Apple Care but was wondering if other people have had the same issues and how Apple handled it - I need the laptop for work so can't just wait a week for a repair.