ICMP: Type:11 Code:0 showing in firewall

I seem to be getting about 3 of these ICMP: Type:11 Code:0 showing in my firewall a SECOND. I have found out this and unreachable address that something is trying to call. But how do I find out what ?. Does anybody know of a TCP port sniffer ?
My firewall (look'n'stop) shows only Nod32,WLMessenger, CfosSpeed(network balancer), and maxthon showing as connected. I have a dual boot system and with the second system with the SAME 4 things connected there are NO ICMP: Type:11 Code:0 entries in the firewall.
Thanks

 

A packet sniffer like Wireshark should give you information on ICMP packets but, so should your firewall logs, I'd think. Regardless, Wireshark should show you source and destination IP. In an ICMP packet with a type 11 and a code 0 means that the packet's time to live (TTL) exceeded in transit.