We recently bought a new Macbook Air and since day 1 have had problems with the power cord not charging the computer after it's been unplugged for awhile. I found the fix online where you press the right combination of keys and it magically reactivates the power cord, but it's getting old having to do this every single time we take it off power to use it on battery. Is there a more permanent fix for this? Can they do anything at the Apple store to fix it, or should we ask them to replace it?