It seems weird but, sometimes my settings about showing chat messages before you enter the lobby change into default 0. I don't know what happens to the pc, but it doesn't have relationship with restarting pc. I usally play 0 ad two times a week, so i don't know what happens. BTW, right now if you host and you go back to the main lobby screen, the chat is cleared. I think it would be nice to preserve the chat. Don't know/remember if it happens with joining a game and then going back. It doesn't happen after playing a match. cheers