Could be a bad display profile, but I'm going to guess it's a shader bug with your video card.
What OS version are you using?
Have you updated the video card driver from the GPU maker's website recently?
Thanks for the reply. I'm currently running Mac OS 10.9 with an AMD Radeon HD 6970M 2048 MB card. Since Macs only update the driver through the app store update I haven't downloaded anything from AMD.
Make sure you install the 10.9.1 update.
Another test you can do is disable GPU drawing in Photoshop's preferences, then relaunch Photoshop.
If the problem goes away, then it was caused by the video card driver (or, possibly by a defect in the GPU, but those aren't as common).
I think I solved it. The Nvidia Cuda Toolkit had been installed before. I uninstalled all files and preferences pertaining to that and seems to be working. Thanks for the help!
Ah, that's interesting. I wonder how it was interfering, especially with an AMD GPU that doesn't support CUDA....