1. In a distributed, multinode data processing system in which nodes communicate via adapters coupled to each node, a method for detecting node reachability inconsistencies in the presence of temporary communication failure or temporary daemon blockage, said method comprising: upon detecting at a first node conditions suitable for instituting change in adapter group membership, sending to a recipient node, a message indicative of membership in a previous stable adapter membership group upon the condition that said recipient node is also indicated as being part of said stable group; and initiating a group join protocol in which said message is rejected by a recipient node under a condition selected from the group of conditions consisting of (1) said message includes indicia showing that the sending node and the recipient node are in the same adapter membership class, said indicia being in conflict with corresponding indicia stored within said recipient node; and (2) said message includes indicia showing that the sending node and the recipient node are in different adapter membership classes, said indicia being in conflict with corresponding indicia stored within said recipient node.