Informix 5.01 crash often on IRIX 5.2 ?

Hi We have a Challenge L machine runing IRIX 5.2 and Informix 5.01. The problem is that the database engine will crash several times a day. We check the Infomix log and find lots of records of abnormal aborted user process. We think these process terminate at the critical session and cause the shutdown of Informix server engine. The problem is that we do'nt know what cause these process to terminate abnormally. We are not able to find any regulation from the log. Got any clude? Plese forward this article to anyone you feel may have some idea abut it. Thanks. --ping p.c.liu@cdc.com