Stored procedure executing system calls

Hi there! I have a problem with a stored procedure that is executing a system call. I am on Informix Online 7.22.uc1 on AIX 4.2.1. The problem is that after I have brought the instance online, the stored procedure will execute a few times before failing with a 668 error. I can then take the instance offline and bring it back online again and it will then work. To make it work all the time, all I have to do is start online as root instead of informix. Therefore, I guess it is a resource problem but I can't track what resource is constrained. I don't believe it to be the number of processes a user can execute as I have raised it to 200 and this still did not fix the fault. Any ideas anyone? Danny