Windows: Annoying Problem of dxva_sig.txt

Problem:
Whenever you play a .wmv file, a dxva_sig.txt is generated at the same location as the media file. The dxva_sig.txt contains only the letter B.

Cause:
dxva stands for DirectX Video Acceleration. This problem occurs when the AGP Texture Acceleration feature is enabled on some video cards.

Solution:
1. Start -> Run
2. Type in dxdiag, and press ENTER
3. Under the Display tab, disable the AGP Texture Acceleration DirectX Features



Ref:
dxva_sig appearing on my desktop - TechSpot Troubleshooting