1. A method of processing a link embedded in a link document in a client computer, said link comprises a URL reference for a URL document in the client computer or another computer, there being stored a record containing a link reference and an intended fingerprint, said intended fingerprint representing the content of the URL document associated with the URL of the link at the time of or after the link was created, said method comprising the steps of: fetching the intended fingerprint for the link; fetching the URL document; creating a current fingerprint of the fetched URL document; comparing the intended fingerprint and the current fingerprint; and identifying that the intended fingerprint and the current fingerprint are different in a material way.