DXVA results in green screen after update to windows 8.1

[sapient]

Hello,
I just updated my windows 8 x64 to 8.1 and now when I try to play a video using dxva I get green screen.
I use MPC-HC and the LAV filters, and I have an ATI card with the latest drivers. DXVA was working fine in windows 8, but it stopped after I updated (in place) to 8.1
Any ideas how to fix this?

[JanWillem32]

The Windows 8.1 driver is still in beta. It has its flaws. http://forums.amd.com/game/messageview.cfm?catid=454&threadid=166585&enterthread=y
(The changes in this specific driver will be added to the mainstream driver in a future version.)

[sapient]

I actually did not change the driver after updating to 8.1
I still have the same driver I had in windows 8, which was working fine (that is the AMD driver, not the microsoft one).
Since I have an HD4870 card, I am using the 13.1 driver (the latest to support this card).
So, since the driver is the same, and it supports DXVA, it must have something to do with windows 8.1, I am guessing...

[nevcairiel]

You may need a new driver for Windows 8.1 to resolve such issues, however for such an older card it may be problematic to get one. Even the HD 7xxx series doesn't have an official driver yet, beside the odd beta driver they "released" on their forum.

[sapient]

I solved it myself.
During the update, HyperV was turned back on, and it produces this effect.
I turned hyperV back off again and DXVA works again.