Block magic 4114

One of our servers ( instances ) has suddenly started coming down quite often with the following message. 4:36:32 Checkpoint Completed: duration was 2 seconds. 14:37:56 Pool = 0xc2b1b010, Pool name = mt, Blkhdr = 0xc32c85e0 14:37:56 Block magic is -4114 (BL_MAGIC_FREE), expecting 4 14:37:56 Memory block possibly freed twice 14:37:56 mtshpool.c, line 2535, thread 26118, proc id 12339, Condition Failed ( CHECK_ALLOC_BLOCK), In (mt_shm_free) Thread(26118, sqlexec, 0, 3). 14:37:56 PANIC: Attempting to bring system down We 're on an HP 9000 with Informix 7.1. Any ideas of what is causing this ? Thanks ciao p ****************************************************************************** Peter Wages EDS Arlington, Virginia pmwages@cais.com Work: (703) 741-7436 Home: (202) 244-3511 Anywhere is walking distance, if you have the time ******************************************************************************