I/O Bad request chunk 3999 Informix 5.0

Got the following failure message and try to understand the problem. The solution given by Informix did not work (unload tables, drop and recreate database then reload the data). Problem recurred immediatly after recreating the database. Platform: UNIX SCO 3.2v4.2 Informix engine: Online SQL 5.00 Engine configured with 2 chunks and transaction logging First clue: any attempt to backup (tbtape) aborts with the message "Program cancelled". Second clue: the Informix engine log show the following error messages Checkpoint completed I/O bad request chunk 3999, pagenum 687799, pagecnt 1 Level 0 Archive cancelled Third clue: when attempting to use the "tbtape -s" again, got a "Segmentation Violation". Multiple message with "Process Aborted Abnormally " showing in the Informix log. Fourth clue: The Informix log reports "Pages failing consistency check". THE SYSTEM IS UP BUT IT IS IMPOSSIBLE TO BACKUP THE INFORMATION Where is the chunk 3999 reference coming from? The Informix Support solution did not work, is there an answer other than re-initializing the Online Engine? Is there a good soul out there who knows what to do? proussel@ix.netcom.com