I've figured out that, for whatever reason, something doesn't like black backgrounds. When I reinstalled the OS, i didn't reactivate Windows 7 (lazy) so a few days later, the OS reminded me by setting my desktop to a solid black background and displaying "not genuine" in the lower right corner. I reactivated, but I didn't change the background back. I also figured out that making something happen on screen will bring the screen back up (i.e. pressing the windows key to make the start menu come up.) so I set the background back to the windows 7 default and now the screen doesn't fade anymore.
That being said, I still don't know why that happens. Just some more information.