Recorded Video is sped up

[AxelFuentes]

I've been trying to record my Half-Life 2 Let's Play, but whenever I record anything, the video is all sped up and ends before the audio does.
Here it is in sony vegas:

I've been having this problem for weeks now, and I've tried the following solutions:

-Playing and recording in 720p, AVI format
-Playing and recording in 720p, but in windowed mode
-lowering the framerate
-setting Action's priority to high on the task manager

But the video is still sped up. Solutions please?

PC Specs:
-Windows 10 64-Bit
-8 GB Ram
-Intel Core i7 5th Gen, 2.40 GHz
-Nvidia GEForce 840M


Action Settings:
-AVI Format
-720p Video Size
-60 FPS

[AxelFuentes]

Okay, I just tried this solution that I found on Youtube of setting the priority of other Action! processes to High, but it doesn't really help. The video is still sped up when I put it into sony vegas for editing.

[radi]

Please post a DxDiag report of your PC.