Disable Kerberos / Single Sign-on

We have a Mac mini running OS X 10.7 Server which has a number of shared folders/drives using AFP. We have a user account called fcp setup as sharing only which coworkers use to access the shared files. Whenever a coworker clicks on the machine in finder we get prompted for a Kerberos password: We can get around this simply by clicking cancel (and we are then presented with the classic login window), but it confuses people. **How can I disable single signon/kerberos?** (or alternatively, would it just be better to configure it properly? and if so what are the benifits since we only use filesharing?) *I assume this is something that comes activated with server because I dont remember anyone ever 'turning it on'*