First of all, comment out your account name. You don't want to give any nefarious acct hacker folks half of your account information.

Second, it sounds like you may have been keylogged. If you haven't participated in any nefarious activities, but SOMEONE on your account has, it's very likely that your account information might be compromised. There should be some helpful tips on securing your computer and account information in the official WoW Customer Service Forums.