Firewall: Unknown code 00060001

I see this alert coming from a single machine about 100 times within 10 minutes. Anyone have clue what this could mean? I tried doing a search result although came up with nothing. Any assistance would be great. Thanks.

Column Name Value
Firewall Id Firewall 601308
Client Name (pc-name)
Computer Name (pc-name)
MAC Address 001d0938a***
Primary Server 10.32.4.136
Date Received 2009-05-11 12:47:39
Date Occurred 2009-05-11 12:46:44
Level Critical Warning
Event Unknown code 00060001
Source 10.6.8.40
Target ***.**.127.254
Protocol ICMP
Rule
Application
User