1. A system for remote maintenance of user units comprising: a management server; and a plurality of user units connected to the management server via a communication network, each user unit being configured for transmitting to the management server, via the communication network, state data related to hardware and software parameters associated to an operation mode of the user unit; wherein each user unit comprises: a memory configured to store the state data of the user unit comprising variable values related to states of the user unit, values indicating a transition from an initial value of a given state towards a final value of the same state and temporal data associated to the states; a state data monitoring module configured to detect at least one value of a specific state or a transition of a value of a state indicating an operational failure of the user unit; and a state data collecting and transmission module configured to be activated when a failure is detected by the monitoring module, and to extract from the memory and transmit to the management server state data corresponding to current states of the user unit at the moment of the failure; and wherein the management server comprises a module for the reception and analysis of the state data transmitted by each user unit, said module being at least configured to determine a statistic correlation coefficient resulting from a comparison of the values of each state of all the user units with the values of other states of all the user units.