I just spent the better part of today troubleshooting my MacBook Pro 9,1 after a reboot triggered the gray screen of death (circle with a cross through it). I finally discovered that the ordeal I experienced was the handiwork of Trim Enabler. Apparently, my MacBook Pro triggered an automatic Yosemite update, which conflicted with the version of Trim Enabler that was installed on my system. That meant I got to spend most of today training as an Apple Tech—which was a very frustrating and scary ordeal. Especially when I thought I had lost all of my data. Thankfully, with the assistance of a very helpful and knowledgable Senior Apple Technical Support Advisor named Travis, I was able to install El Capitan and restore all of my data. Now, I'm trying to figure out whether I should 1) uninstall Trim Enabler 3.4.2, promptly discard it in the Apple trashcan making sure to set it ablaze, and then run Apple's built-in Trimforce command or 2) upgrade to Disk Sensei. And yes, option two does indeed suggest that I must be masochist to let Trim Enabler or any of it's sister apps near my Mac now or in the future. I would appreciate any help from the experts here to decide on which course of action to take. Thanks!