Ahahahaha. Okay. First, WRONG SECTION anddd second, I have this problem A LOT. Matter of fact everytime i log in through steam. All you have to do is after it says "the steam session has expired", type in your username and password and click "create new account" it should say you already have one and after it says that just click log in and it should work.
+Thank if it Helped If not, I have other ways of getting pass this bastard