Clients Mac logs in after restart with wrong user name

Hi,

I have a problem with AFP login.

After restarting the Mac of a client his Mac automatically logs in to server (an alias of the server volume is in start objects) but it uses a wrong user name which has not the correct rights for accessing the data.

It uses a user named "server" which isn't setup on any place in clients Mac. On server "server" is the name of the local user.

Does anyone know this and is there a solution to avoid this?

Thanks, Almute