frozen screen when i connect it to airplay(apple tv)

hello guys,

two months ago i got the new macbook 12'' Mprocessor , since i need my laptop only for preliminary usages, such as everyday uses, internet surfing and youtube...; i have chosen this model, but even sometimes it does not work properly in doing those basic tasks. when i connect it to apple tv, sometimes i get frozen screen with mixed all the colours and pictures, it seems to me that maybe the graphic chip fail in the process or something similar to that. it happened to me many times, exactly when ever the macbook starts "napping" and i am trying to wake it up, all of sudden everything get frozen and i had to shut it down. i already made an appointment in apple store the guy checked everything and said hardware is ok, engineer department also said there is no issues in terms of software, emailed the tech. support, but so far no useful help from them. any of you guys had the same experience ? any suggestion?

i also attached some of the pics.