One of our servers abended 40 times in a row over the weekend. Below is the first abend log. Any ideas?

Server GS00 halted Saturday, February 7, 2009 9:04:45.653 am
Abend 5 on P00: Server-5.70.04: Page Fault Processor Exception (Error code 00000000)

Registers: EIP in TCPIP.NLM at code start +0004BE05h

Running process: Server 00:8533 Process
Thread Owned by NLM: SERVER.NLM
Stack pointer: A6E06F80
OS Stack limit: A6DFF040
Scheduling priority: 67371008
Wait state: 50500F0 Waiting for work

7CCF6991 (TCPIP.NLM|ICMP_Send_Unreachable+C45)
-7DDF4D14 (TCPIP.NLM|ipMIB+798)
-7DDEC89C (TCPIP.NLM|PIMTunnelList+4)
7CD34FB6 (TCPIP.NLM|ip_local_deliver+8B)
7CD3479B (TCPIP.NLM|IPDeregister+A2)
00363B12 (SERVER.NLM|StartWorkToDo+23)
0022AB77 (SERVER.NLM|kWorkerThread+DF)
00224628 (SERVER.NLM|TcoNewSystemThreadEntryPoint+40)

Additional Information:
The CPU encountered a problem executing code in TCPIP.NLM. The problem may be in that module or in data passed to that module by a process owned by SERVER.NLM.