NSF subsystem error

We have this morning encountered the following error twice. The impact of this is that no new connections to the engine are allowed, but people currently attached have no problems working. In both cases we have had to bounce the engine to give access to all users. Most users connect to the main application via shared memory. Any ideas anyone ? 08:48:24 Informix Dynamic Server Initialized -- Shared MemoryInitialized. 08:48:24 Physical Recovery Started. 08:48:24 Physical Recovery Complete: 0 Pages Restored. 08:48:24 Logical Recovery Started. 08:48:28 Logical Recovery Complete. 0 Committed, 0 Rolled Back, 0 Open, 0 Bad Locks 08:48:30 Dataskip is now OFF for all dbspaces 08:48:31 On-Line Mode 08:48:31 Checkpoint Completed: duration was 0 seconds. 08:48:31 listener-thread: err = -27100: oserr = 5: errstr = : InternalCommunic ations Error: NSF subsystem error. System error = 5. 08:48:31 Attempting to bring listener thread down. 08:48:31 Server stopped. Regards Mr Creosote Informix Dynamic Server 7.31.UC2 SCO OpenServer 5.0.4 -- "Just a waffer thin mint?" Sent via Deja.com http://www.deja.com/ Before you buy.