As a troubleshooting step you can try installing the graphics driver that appears on the ASRock website using the link below:
You can also try using the generic version that we provide based on the graphics controller of your processor. You can download it on the link below:
Please let me know your findings.
I already tried both your suggestions before I posted on this page. It didn't resolve my problem
Anyway a couple weeks later my motherboard died... I got a replacement and what do you know, the problem was fixed!!!
No more losing signal after the windows loading screen.