It worked perfectly in Windows 10, I downgraded just because Vegas Pro 13 doesn't work there but now its Action! what it's not working...

Also, I have already tried uninstalling and cleaning the register but it does not work either. I remember downloading the software a couple of months ago and having the same problem.
Thank you.
OS: Windows 8
Video Card: Nvidia GTX 970
Memory: 12 GB
Monitor Resolution: 1920x1080
EDIT:
I saw a tutorial with a fix that worked, I had to change my Monitor refresh rate to 60Ghz on the Nvidia control panel and now it works. Just like this: http://gyazo.com/67ff2e3cbc7bf959911079c340b56a3c
The tutorial was this one: https://www.youtube.com/watch?v=cdAhsYxHXPM