I have a "mid-2012" MacBook Pro Retina, and I've been having a few issues lately. Every time I boot my computer, I have black letterbox bars on the boot screen. So I reset my PRAM and everything is fine for one boot. Then I reboot, and it's back to it's letterboxed boot sequence. What's going on? I've been having some real performance issues in my finder, safari, Adobe Premiere, and video games such as TF2. Lots of lag, lots of crashing, lots of memory leaks (in the case of Premiere, but I think that's an Adobe-side issue). Whereas my computer used to handle full video settings at 1080p in TF2, now I'm getting lag at less res with the lowest video settings. Safari is often lagging and crashing, as is the finder. There are a few other issues that have been happening consistently, but I am forgetting them right now. It's still a completely usable computer, but there is definitely something wrong. I feel like the PRAM reset not persisting may be the key. Basically, it's not running smoothly, and with the boot sequence always behaving abnormally, and requiring PRAM resets to remedy (but only for a short while), I'm beginning to suspect that there is something malfunctioning from within the computer. It's been getting worse and worse. Does anyone have any ideas as to what this could be? I'll be making a Genius appointment soon, but I am trying to deliver a video project at the moment. And yes, I have wiped and reinstalled a fresh OS many times (from my USB and from Apple's servers). I have also tried the new Yosemite Beta 5, but that didn't do anything, either. Same issues. Oh, and I'm sitting at 12.43GB of ram used with only Safari open with only 3 tabs. I keep hitting my memory's ceiling without intensive programs runing.