As per Microsoft:
Explanation: A ping of death attack was attempted against a computer protected by ISA Server. This alert occurs when a large amount of information is appended to an Internet Control Message Protocol (ICMP) echo request (a ping) packet. If this attack is successful, the computer crashes.
User Action: If logging for dropped packets has been set, you can view details of this attack in the packet filter log in the ISALogs folder, which is located under the ISA Server installation folder. You can use this log to monitor intruder activity. Steps against intruder activity include setting up a static packet filter to block incoming ICMP packets or enabling the filtering of IP fragments by using ISA Management. To enable filtering, in the ISA Management console tree, click Servers and Arrays, click Name, click Access Policy, click IP Packet Filters properties, and then click the Packet Filters tab.