HamdenPro: do not know how I am getting these random invites but am open to additional theories if you have them. : )
Anyone really could just send an invite by typing in your user name whether you are friends or not. So it is likely those trying are just taking a shot in the dark for whatever reason. If you are online in game window, even in hiding, you will still see the invite... if you decline the invite it will tell them you are online, if you let it time out, they may not know, but if you are not on line it would come up player not available or something like that. Being online in the forum will not allow for game invites to go out and you will appear off line.