I have the same problem too. The client stops working after i select my character, Error. I did manage to log out and in immediately after the clan war without any problems, and the problem only started this morning when i tried to login. I doubt its the problem with the items (I have even transferred the items from clan war to another new character on the same account and that character could still login normally - and if it was a problem with the items, which were in my sotrage, it should have affected my other character as well). I suppose its something wrong with my character, but not pertaining to the clan war items, because i manged to relog once or more after that. Also, yesterday night, my last login ended in a dc, and i didnt try to login after that. Not sure if thats the cause
On a side note, I have tried what MaShadows recommended, but it didnt work for me. I have also tried reinstalling, running Triggerdetect and checkall etc, but all with no effect.