I've been getting this error quite frequently as of late. I've no idea why either. I haven't given out my account serial or anything, and it seems unlikely there is a dude out there hacking people's Warband passwords so he could play on their account.
So yeah, I really don't know what's going on. I am getting the "Lost connection to server" error once in a while, and when I try to log on again it says "Profile name used by another person", or something like that. However, when I try to log on again, the error disappears and I connect to the server.
I am also getting occasional lag spikes up to 300 ping if that's worth anything. Also, I this problem still occurs even after I changed my password.
So...yeah, I think that's everything. Advice would be really helpful, or if it's possible to check a log for the IP of the other person logging on my account.