Premiere Pro and Mac OS X 10.9.3
UPDATE: Many users are reporting that the recent release of Mac OS X 10.9.4 has resolved these issues.
We are aware of an issue affecting users of Adobe Premiere Pro and Adobe Media Encoder on Mac OS X 10.9.3, where exports using the GPU can display unwanted artifacts. We are currently working with Apple on a fix, but unfortunately cannot yet estimate a timeframe for this. If possible, we recommend that users stay on OS X 10.9.2; if the upgrade has already been installed, then the current workaround is to disable the GPU during export.