Informix -753 error message

Informix We have a single-user version of informix (not including root), and have been having different users accessing the informix at different times. One day the system replied -753 when a user "informix" attempted to select one of the databses. Since I am each user, I know that there is actually just the user getting the -753 error message. ie there are no other users using the system when this error message is received by "informix", or whatever other user happens to be selecting a database. The -753 error message even occurs when the user accessing the database owns the database and most of the tables in it. NOTE: root does not get this error. All the users were dba privileged when the error started occurring, and the user receiving the error message was in fact the only user using the system. The users "root" and "informix" now have dba, while the other users only have connect (including user "public"). While it is possible to run our software under user "root", this is inconvenient, and we know that it used to be possible to have other users accessing the database. Hardware is HP Netserver, running latest(?) SCO unix system V, version 3.something, We have Informix ESQL, ONLINE engine. The problem usually manifests itself in dbaccess. Sincerely yours, Joseph R. Kerlin Transportation Management Solutions, Inc. [12~