Its a pretty old stuff and it happens when you watch the replay of a player who is not in your normal ranking list( you can see the players 30 ahead and 30 behind you in the rankings.. for you around 4810-4870) and you checked out a players replay (from the players online list) who wasnt in between these two numbers. This happens when you watch the replay until the end. But if you dont watch the replay until the end.. for example quit before the last move you see a different sign where you can click on the X button. After that you cant go back to the chat or anything. You have to watch some of the players replay between rank 4810-4870 and after that you can go everywhere. Already told the devs like 2 years ago but you know... no money on fixing this.
So the two solutions you can do:
1: quit the replay before it ends and click on the X and watch a replay from a player you can see in your normal (not online list) then you can go everywhere
2: you only watch replays from between 4810-4870 or from the clan rankings
I see you have a hungarian flag so if you want I can explain it to you in hungarian too.