I use an early 2011 (also known as a just-out-of-warranty) 13-inch Macbook Pro. I bought and installed Photoshop CS6, and for the first week everything was great. Then it started what Adobe refers to as a "redraw" glitch in which it would randomly add blocks of color across my image or delete portions of it completely.
So I contacted Adobe and their technical support. They told me "The only time people are seeing redraw problems like this is with bad video card drivers, defective GPUs, defective RAM, and sometimes defective CPUs." Well, that sounded like a hardware problem so I took my computer over to the Apple store.
After an hour of different testing, Apple told me that my computer was performing fine and since the issue only occurred in Photoshop, that means it is highly likely that it's a problem with Photoshop and not the computer. So back to Adobe's technical support.
I was told that "Apple's hardware diagnostics are not known for being complete, robust, or overly accurate" and that the problem is definitely with my computer, and definitely not a fault of Photoshop. I found out that I can disable using my GPU in Photoshop's preferences, but even after doing that I still get a glitch. After telling Adobe this new information, they again repeated that it is a problem with my hardware and I should contact Apple. Apple again says that all of their diagnostics tests have come back normal, and that since the issue only occurs in Photoshop I should get Adobe to help me fix it.
Quick version: I experience a redraw glitch whenever I use Adobe Photoshop. Apple ran some tests and said my computer functions normally, whilst Adobe is saying that the only reason I'm seeing the glitch is because of a hardware issue.