What's wrong with my client, or did i do something wrong?

Hi, i've encountered a problem with my clients. I've played on Wotlk Icecrown with no problems before, but yesterday i downloaded Cata client, played it for a while, and after one logout the client doesn't work anymore, and name has changed to World of Warcraft Retail. Wotlk client worked for once yesterday, but today the same error occured on it too. Reloading clients doesn't seem to help the problem, so i'd appreciate any help here. Thanks.