Thanks, buddy. Every website and YouTube video mentions that the grayscale issue is there because Windows 10 includes a mode to help people with color blindness, but the color filters thing with turning it off still won't work. I might mess with it some more tonight after I get home from work. Frustrating though.
Yeah, my first thought was that you enabled some obscure grayscale mode by mistake. Are you getting this issue even during the early/middle stages of the Windows installation process, or does it only occur once the installation is finalized? I assume you already tried reinstalling the OS and/or the video card drivers? I'd also try using a different video card, cable, and/or monitor just to further rule out a hardware issue. Other than that, I got nothing.
EDIT: You said you did a fresh install. Did you try an upgrade with W7 already installed? Curious what happens there.