"This computer's local hostname "my-mac-mini.local." is already in use on this network. The name has been changed to "my-mac-mini-2.local". To change the local hostname, open System Preferences and click Sharing, then click "Edit" and type the name in the Local Hostname field. I haven't touched anything in System Preferences or done anything different from what I normally do. This is the first time I've seen this message and I'm afraid somebody has access to my computer or something worse. I clicked OK and my macmini is working fine but I haven't seen this in the 2 years I've owned my macmini. What should I do?