That is simple. As documented in the install memo, LISTSERV needs
access to the disk containing BITEARN NODES, XMAILER NAMES, and DOMAIN NAMES.
I would check LISTSERV's PROFILE EXEC to make sure that the disk is
accessed. You might want to logon as LISTSERV and enter
CMS Q SEARCH
to have LISTSERV reveal what it is currently accessed to.