You have an account in use error, just wait 10 minutes. Kabam is so retarded, to "fix" the muledump dupe they made it so that you can't receive the char/list page if you're logged in. So when you get an account in use error, you have to wait 10 minutes before you can load the main menu.
I find that many have this problem and now made a tutorial (:P)
There are 3 methods to solve the problem
1st :
As @059 said wait 10 Minutes and then play the game [Which is too long , so follow the 3rd/2nd steps]
2nd :
Switch off your modem , wait 10 secs and then switch it back on and play
3rd :
Downlaod Hotspot Shield (VPN) [Google it]
Once you get the error , close the client . Open Hotspot Shield and hit Connect .
Wait till it connects and now you are ready to play [You can also use the VPN proxy if you want to hide ur IP ]
If you reconnect too much and get the error again , Hit Pause to return to your normal IP and play.
Now your geared to play . No more delays