Abstract: Method of dealing with faults in a fault-tolerant distributed computer system, as well as such a system, with a plurality of node computers (K1 . . . K4) which are connected by means of communication channels (c11 . . . c42) and access to the channels takes place according to a cyclic time slicing method. Messages leaving node computers (K1 . . . K4) are checked by independently formed guardians (GUA) which convert a message burdened with an SOS (“slightly off specification”) fault either into a correct message or into a message which can be recognised by all node computers as clearly incorrect.