SELECT statament running slow until terminated with 25587 error c

Hi all, IDS 7.30.UC5 Sun Solaris 2.6 I'm trying to run SQL statement as follows: SELECT ... FROM tbA,tbB,tbC WHERE ... INTO TEMP tmp1 WITH NO LOG CREATE INDEX tmp1_1 ON tmp1 (... , ...) SELECT ... FROM tmp1,tbD WHERE ... INTO TEMP tmpfinal WITH NO LOG DROP TABLE tmp1 Most of the time, this SQL statement will only take few minutes to complete. But sometime it would take up to few hours (around 10 hours) and terminated with error code 25587. 25587 - Network receive failed A system call has failed. Perform a DISCONNECT and check the the status of server. See your UNIX system administrator for assistance. When I check the status of the server and the Informix engine, all are working fine. Each table has around 50K of records only. Does anyone out there know what is the problem? Thanks for any answers,