Launcher window goes completely grey after invalid session when opening after minimising before invalid session

I'm sorry that the attachment image is so big, when I dragged it onto the window it just came out really big. I don't know how to fix it.

I also don't know if this is my fault, or if it's my OS's fault. This has never happened to me before, so I don't know if it's like an issue related to an expired session, or if I just never closed the launcher window for so long it just gave up, because I'd normally leave my Minecraft Launcher window open all the time so when I need to use it I can just open it in a split second. My only question is: Does that relate to what I assume is an expired session (me leaving the window open all the time)?