I encountered the same problem at OS startup because Linux renamed the links auf my Informix startup scripts. The link names where changed form e.g. S21informix to S01informix. Because of this the database server instance was started BEFORE the network services where available ! As I found out later, SuSE Linux uses a new mechanism to (re)set the order of startup scripts depending on some header information in the script files themselves.
So, the simple reason for this "error" may be that network services are not available at startup of the database.