Hi, I have a refurbished 2012 11" MacBook Air. 2.0GHz i7, 8 GB RAM, 256 GB SSD. Purchased it about 6-7 months ago directly from Apple. I've never had any troubles with it. Once in a while I reinstall the OS just to speed it up a little bit. I notice slight lag over time if I install some applications and whatnot, so I'd say I've reinstalled 10.8 Mountain Lion about 3-4 times. Being that type of person, liking everything clean and fresh and crisply running, I decided to run the Apple Hardware Test just for the heck of it, despite not having any issues. It comes up with error code 4HDD/11/40000000:SATA(0,0). I have no idea why that would be. It's obviously something to do with my hard drive, but I've never experienced an issue with my hard drive and had no reason for concern prior to running this test. Has anyone else seen this before? Do you know what it is? And what should my plan of action be? Do I need to take it into an Apple store to have them have a look and diagnose the problem? Thanks in advance for your input.