Dear Sir: I am testing UDP-sender.exe and UDP-receiver.exe under WinXP with following commands. But a error (marked by red color) happens after the server transfers data once. Under linux, I have never met this problem. I am wonder if there is a bug? UDP-sender: C:\Documents and Settings\hwsun.PSL-AD\Desktop\UDPCast-run>udp-sender -f test.tx t -P 5004 -M 239.1.1.1 --daemon-mode --nokbd --min-receivers 1 Udp-sender 2007-02-05 Using mcast address 234.81.112.185 UDP sender for test.txt at 10.81.112.185 on Intel(R) PRO/100 VE Network Connecti on - Packet Scheduler Miniport (00-00-e2-5b-c7-66) Broadcasting control to 239.1.1.1 New connection from 10.81.112.185 (#0) 00000009 Starting transfer: 00000009 bytes= 1 230 re-xmits=0000000 ( 0.0%) slice=0000 1 230 - 0 Transfer complete. Disconnecting #0 (10.81.112.185) bind socket to 10.81.112.185:5005 (Bad file descriptor) <------------ why??? UDP-receiver: C:\Documents and Settings\hwsun.PSL-AD\Desktop\UDPCast-run>udp-receiver -f mytes t.txt -P 5004 -M 239.1.1.1 --nokbd Udp-receiver 2007-02-05 UDP receiver for mytest.txt at 10.81.112.185 on Intel(R) PRO/100 VE Network Conn ection - Packet Scheduler Miniport (00-00-e2-5b-c7-66) received message, cap=00000009 Connected as #0 to 10.81.112.185 Listening to multicast on 234.81.112.185 bytes= 1 230 ( 0.01 Mbps) 1 230 Transfer complete. Best Regards, Mr. Haiwei Sun R&D Engineer Panasonic Singapore Laboratories Pte Ltd Singapore