My 2011 13" MBA is failing the Apple Hardware Test (pressing "D" upon bootup) I run the Quick Test (3 minutes) for over half an hour. but it only says Time Elapsed: 48 seconds, and my cursor still moves. Still, it estimates at 3 minutes, it shouldn't take close to an hour. I took it to the store, and it passed all their tests, and they recommend sending it in to replace the motherboard for $300. The reason I performed these tests is because my laptop will occasionally and randomly, I can't recreate it) freeze during use. It's had these freezes since I bought it though, so I thought it was always on me. Any idea as to why it fails AHT, but passes in store?