1. A method of protecting data items in an organizational computer network, comprising: a) defining by a protection management server on a general purpose computer, multiple information profiles for classifying data items; b) defining protection policy rules, by an administration console, for protecting a data item belonging to a specific information profile; c) responsive to a first event being associated with the existence of said data item, and initiated by an authorized user or application, and before said authorized user or application has control on said data item, performing the following steps, by a host computer hosting said data item: c.1) intercepting and interrupting all content access and taking control of all content access to said data item by said authorized user or application; c.2) analyzing one or more of the following: the source location associated with said event; the destination location associated with said event; the user or application associated with said event; the content of said data item, said content being the data portion of said data item; and the metadata of said data item; c.3) classifying the data item according to the analysis results and to the defined information profiles; c.4) protecting said data item by transforming the content and the form of said data item, based on said classification and the defined protection policy rules; c.5) changing said data item to its transformed form which is independent of any storage location or of its way of transmission; d) terminating interruption and returning control on said data item to said user or application; and e) responsive to said event, allowing, by said host computer, access of said authorized user or application or of other users to said data item, only in its transformed form, and according to said classification and to said defined protection policy rules, wherein enforced protection applied to the data item responsive to said event is updated, according to said classification and defined protection policy rules.