I have a HP 6t-1200 CTO Ultrabook with the Radeon HD 8750M and Intel 4000 switchable graphics.
Problem: When I am operating with Windows 8 they function normally, but upon updating to Windows 8.1 the AMD drivers fail to be able to initiate and D3D.
1. Most current driver is dated 2013-01-14
2. Generic drivers do not recognize the hardware
3. Drivers for other HD 8xxx series based HP laptops do not resolve the problem
Current workaround: Open the Catalyst Control Center and go to switchable graphics application settings under the power tab. Switch anything that uses DirectX to run in power saving mode, this will run those applications using the intel 4000 graphics which has a more current driver that works with Windows 8.1.
Solution: For now I believe that the only solution is to wait for HP and Microsoft to work together on creating a newer driver. Once that newer driver is released it should resolve the problem. The other solution is to permanently stick to Windows 8 and not update to Windows 8.1. This is a bit more difficult though since Microsoft pushes 8.1 very aggressively. There might be a way to make the notifications and automatic attempts to update stop, but I have not looked into that solution.
If you know of a solution or a better workaround than what I have posted please share it with the forums. I can only hope that HP is working on creating a newer driver and releasing it as soon as possible. If there is anyone that knows of a release date of a potentially newer driver from HP please also share.