I had a similar problem with a dual monitor situation. Well, I finally got a response back from Sapphire which they suggested I do a windows update to make sure I had all the correct pieces of the OS in place, and then install the latest beta drivers, 13.6 beta 2. The issue I had was with the audio, but also having two different monitors hooked up at the same time. AMD/ATI also have their own driver uninstall app which I highly recommend using before installing the new drivers.
1. Uninstall AMD Catalyst through Windows control panel
2. When prompted, uninstall all remaining components
3. Run the AMD/ATI uninstall app
4. Re-start Windows
5. I made sure both displays I wanted to use were on
6. Install the beta drivers
This did the trick for me, maybe give it a try.