On Monday, July 9th, my 15in, 2012 non-retina MBP froze up on my three different times. I had to shut the laptop off and on all three times to get it working again. I frequently use Chrome (newest version with the GPU acceleration turned off) and Parallels, so I attributed the freezes to one or both of those programs. I bought the MBP the moment they became available in the Apple store. I put an Intel 520 SSD into the MacBook Pro the moment I received it. The laptop (with the SSD) has run great until July 9th... On Thursday, July 12th, my MBP froze up again (I was using Chrome and Parallels at the time.) I shut it off, and turned it back on...this time, the machine did not immediately boot. The machine turned on, but I got a black screen. I turned it off, turned it back on, and I got to the grey Apple screen, but nothing more. Hmm. I turned it off again, reset the SMC ,then reset the PRAM three times in a row, and the machine was still only reaching the grey Apple screen. I turned it off again, left it off for a few minutes, and turned it back on. The machine got all the way to desktop, but froze up after only using it for a few seconds. (I did not use chrome nor Parallels.) Turned it off again, turned it back on, and basically everything I described in this paragraph happened again... A few hours later, I got the bright idea to try my external HD backup drive. The backup drive is a duplicate (used Carbon copy) of the SSD currently in the laptop. I booted from the backup drive. It got me all the way to the desktop, but same problem as before (I did not use chrome nor Parallels.), the laptop froze after a few seconds of use. I then decided to give the original HD that came with the laptop a try. Like I said earlier, I put an SSD into the MBP the moment I got it, so the HD that came with the laptop is practically un-altered. Certainly no chrome, Parallels, or any other third-party apps are on the original HD. I removed the SSD and put the original HD into the laptop. I reset the SMC and PRAM again. I turned on the laptop and it took me all the way to the desktop, but froze up again after a few seconds of use (I did not use chrome nor Parallels. Those two programs arent even on the original HD.) I turned it off, and back on. This time while booting up, I get the infamous kernel panic message (have never received this message before during these troubles.) I turned the computer off, turned it back on (keep in mind that the original, practically un-altered HD is still in the laptop) and it booted all the way to the desktop. Lo and behold, the computer kept running! I used it for a while, and it didnt freeze. I decided to put the SSD back in the laptop, and now the computer seems to be running correctly with the SSD back in it! No freezes so far. I have been using Chrome (newest version, with the GPU acceleration turned off.) I havent tried parallels yet. So now I have the following questions... - What happened? - Why did it happen? - Should I take this laptop to an Apple store to get fixed/replaced? - Could the kernel panic have fixed some kind of internal setting/ROM in the laptop? Remember, the laptop is now working correctly with the original HD where the kernel panic took place, and now working correctly with the SSD (it was previously not working correctly with either.) - Could Parallels have made some kind of permanent change to an internal setting/ROM in the MBP, and replacing the SSD with a HD that did not contain parallels failed to fix the problem?