I have found that rpc.yppasswdd dies every time you run "yppasswd username". I have confirmed this with several other members of hedwig-list. Thorsten Kukuk had no answer as he can not replicate the problem on their os. I have updated the yp tools to the latest ypserv-1.3.6.92 vintage and the problem remains. The mail list members that are experiencing the same problem that I am, all agree that it has nothing to do with pilot error on yp client installations as we get the same errors on hpux, Tru64UNIX, Redhat Linux, etc etc etc.
*** This bug has been marked as a duplicate of 3126 ***