Help please, someone. I've just noticed that in my Finder window sidebar, under "Shared", I have a character called Thomson listed. I don't know any Thomson and I bought the machine, an MBA, brand new. However, I did have an engineer instal the machine in my apartment and can only assume he's the mysterious Thomson. Anyway, whoever he/she is, I don't want him/her on my machine as Shared & "connected as guest". The point is, I cannot find a way to delete Thomson!! Can anyone help? I've tried System Preferences>Security and Accounts and there's no trace of Thomson there. Right clicking on Thomson in the sidebar of Finder only gives me the option to Open and Get Info. Most annoying, this. There MUST be a way to delete a Sharing but totally unwanted guest....