NO RESPONSE FROM SERVER PROCESS

Help me,please !!!!! I use INFORMIX V.7.2 on IBM RISC/6000,AIX V.4.1.4. (memory 256 MB,2 cpu) I have some problem: When my user can't connect to database (through ODBC) he tells me. And in that time I call "onstat -i" it has error messages: "NO RESPONSE FROM SERVER PROCESS" but it still display the correct results. I can't call "onmonitor" or kill any session. I can't shutdown or restart informix. When the error occurs INFORMIX can keep any log to "online.log" until I restart it again. I must kill oninit process and restart INFORMIX. It happends about two times a week for 3 months ago. These are some contents in my onconfig.ol7 ( configuration file ). # Physical Log Configuration PHYSDBS rootdbs # Location (dbspace) of physical log PHYSFILE 15000 # Physical log file size (Kbytes) # Logical Log Configuration LOGFILES 8 # Number of logical log files LOGSIZE 500 # Logical log size (Kbytes) # System Configuration SERVERNUM 1 # Unique id corresponding to a OnLineinstance DBSERVERNAME online7 # Name of default database server DBSERVERALIASES onnet7,onfddi # List of alternate dbservernames DEADLOCK_TIMEOUT 60 # Max time to wait of lock indistributed env. RESIDENT 0 # Forced residency flag (Yes = 1, No = 0) MULTIPROCESSOR 1 # 0 for single-processor, 1 formulti-processor NUMCPUVPS 1 # Number of user (cpu) vps SINGLE_CPU_VP 1 # If non-zero, limit number of cpu vpsto one NOAGE 1 # Process aging AFF_SPROC 0 # Affinity start processor AFF_NPROCS 0 # Affinity number of processors # Shared Memory Parameters LOCKS 20000 # Maximum number of locks BUFFERS 30000 # Maximum number of shared buffers NUMAIOVPS 2 # Number of IO vps PHYSBUFF 128 # Physical log buffer size (Kbytes) LOGBUFF 128 # Logical log buffer size (Kbytes)LOGSMAX 20 # Maximum number of logical log files CLEANERS 6 # Number of buffer cleaner processes SHMBASE 0x30000000 # Shared memory base address SHMVIRTSIZE 8000 # initial virtual shared memory segmentsize SHMADD 8192 # Size of new shared memory segments (Kbytes) SHMTOTAL 0 # Total shared memory (Kbytes). 0=>unlimited CKPTINTVL 300 # Check point interval (in sec) LRUS 4 # Number of LRU queues LRU_MAX_DIRTY 10 # LRU percent dirty begin cleaning limit LRU_MIN_DIRTY 5 # LRU percent dirty end cleaning limit LTXHWM 50 LTXEHWM 60 # Long transaction high water mark (exclusive) TXTIMEOUT 0x190 # Transaction timeout (in sec) STACKSIZE 128 # Stack size (Kbytes) OFF_RECVRY_THREADS 10 # Default number of offline workerthreads ON_RECVRY_THREADS 1 # Default number of online workerthreads DRAUTO 0 # DR automatic switchover DRINTERVAL 30 # DR max time between DR buffer flushes (in sec) DRTIMEOUT 30 # DR network timeout (in sec)DRLOSTFOUND /informix7/etc/dr.lostfound # DR lost+found file path RA_PAGES 256 # Number of pages to attempt to readahead RA_THRESHOLD 128 # Number of pages left before next groupDBSPACETEMP tempdbs1,tempdbs2,tempdbs3,tempdbs4 # Default temp dbspaces DUMPDIR /tmp # Preserve diagnostics in this directory DUMPSHMEM 1 # Dump a copy of shared memory DUMPGCORE 0 # Dump a core image using 'gcore' DUMPCORE 0 # Dump a core image (Warning:this aborts OnLine) DUMPCNT 1 # Number of shared memory or gcore dumpsfor FILLFACTOR 90 # Fill factor for building indexes USEOSTIME 0 # 0: use internal time(fast), 1: get time from OS(slow) MAX_PDQPRIORITY 50 # Maximum allowed pdqpriority DS_MAX_QUERIES 30 # Maximum number of decision supportqueries DS_TOTAL_MEMORY # Decision support memory (Kbytes) DS_MAX_SCANS 40 # Maximum number of decision supportscans DATASKIP off # List of dbspaces to skip OPTCOMPIND 0 # To hint the optimizer ONDBSPACEDOWN 1 # Dbspace down option: 0 = CONTINUE, 1 = ABORT, 2 = WAIT NETTYPE ipcshm,1,60,NET # Override sqlhosts nettype parameters NETTYPE soctcp,1,60,CPU # Override sqlhosts nettype parameters LBU_PRESERVE 0 # Preserve last log for log backup OPCACHEMAX 0 # Maximum optical cache size (Kbytes) BAR_ACT_LOG /tmp/bar_act.log BAR_MAX_BACKUP 0 BAR_RETRY 1 BAR_NB_XPORT_COUNT 10 BAR_XFER_BUF_SIZE 31 HETERO_COMMIT 0 thanks for your kindness. BYE.