So, it’s actually not just a gray screen, but each time I launch unity it keeps changing so quickly between a gray screen and a white screen (this one actually has the sign in option, but it doesn’t work). I deleted the appdata and also uninstalled unity, but when I reinstalled it I got the same problem. I also tried to use 2017.1.2 version but the problem remains.
I’m working on Windows 10.
I have exactly the same problem ! On Windows 10 too.