Hi Yenefer
I too am having the same problem for the last 24hrs now.  I've tried a number of things to sort out this problem but it hasn't help me, maybe u will have better luck.  
Check and update you flash player - mine was latest version
try logging in using browser - I tried explora and chrome, both failed
clear cache 
reload client and game loader - I have done this twice, even found an older version of client and still was blocked.
I even tried to log in from someone elses laptop to make sure the problem was on my laptop - I was still blocked
make sure your firewall is off.  
I hope one of these step resolve your log in problem and you are able to continue with your game play.  should anyone else have suggestions which I have over looked please feel free to suggest them below.