OnLine Error - Network down (25588)

We are running 7.11.UC1: From dbaccess received: -25588 appl proc cannot connect to OnLine server. From onmonitor: WARNING: Network down When we tried to bring the server down it hung. (Tried: onmode -ky; onmode - uy; onmonitor shutdown immediate & normal). We killed the oninit processes as root which allowed us to shutdown normal from onmonitor. We rebooted the machine after that and things look fine. There are no errors in any of the log files. We're stumped. We've been running Informix for more than four years and nobody has ever seen this problem before. The questions: Has anybody seen this before? What caused it to happen? Did we do the right thing? Is there a way to prevent this in the future? Carol Schultheis GIS DBA Team