I just recently purchased a samsung 840 evo for my Late 2011 17in MacBook Pro. I installed the drive November 5th and everything was going smoothly until two days ago. The computer started having random lock ups and sbbod. I checked the SMART status and it's says it's alright. I noticed though that when I went to try and use disk utility through my USB mavericks boot drive that sometimes the SSD would show up in disk utilities. Other times it wouldn't. And when it would show up it won't let me erase the drive. It also doesn't show up as Macintosh HD all the time either. It shows up as disk 02 as the partition or something like that underneath where it says samsung 840 EVO. One of the times it went to boot it also gave me the question mark in the folder icon. My question is is the drive defective or is it incompatible with my MacBook Pro.