assert failed

We are running informix 9.21 on AIX 5.1 running a third party software. Just recently, when we run a process to change symbols from the third party software we are getting the following error. Nothing has changed on the server, yet we have gotten this error twice in the last 2-3 weeks. We had never gotten this error before in the 6 months I have been here. Thanks... 22:30:18 Assert Failed: Dynamic Server 2000 must abort 22:30:18 Informix Dynamic Server 2000 Version 9.21.UC4 22:30:18 Who: Session(138270, jweipert@production, 39366, -1609288968) Thread(147105, sqlexec, a0126fb8, 3) File: rsbuff.c Line: 3618 22:30:18 Results: Dynamic Server 2000 must abort 22:30:18 Action: Reinitialize shared memory 22:30:18 stack trace for pid 20142 written to /tmp/af.42896fba 22:30:18 See Also: /tmp/af.42896fba 22:30:27 rsbuff.c, line 3618, thread 147105, proc id 20142, Dynamic Server 2000 must abort. 22:30:27 Fatal error in ADM VP at mt.c:11462 22:30:27 Unexpected virtual processor termination, pid = 20142, exit = 0x100 22:30:27 PANIC: Attempting to bring system down