I am running Windows7x64 and have a VirtualBox Windows XP guest virtual machine running. I am making telnet connections and am running an IMAP client from the Win7 host to the XP guest to an IMAP server running in the guest. Somehow the telnet application (or the IMAP client) on the Win7 host is not seeing the response from the IMAP server - although running Wireshark on the host network adapter shows the traffic being received at the network layer. What's more odd is that the network connection from the closed telnet sessions to the guest shows up in netstat as ESTABLISHED and in TcpView shows the connections as <non-existent>:7912 TCP atacama:58347 192.168.24.96:imap ESTABLISHED <non-existent>:7792 TCP atacama:58361 192.168.24.96:imap ESTABLISHED <non-existent>:5792 TCP atacama:58607 192.168.24.96:imap ESTABLISHED These are the telnet sessions to the IMAP server for the exited client...!! I can make new telnet connections to the IMAP server, but the IMAP greeting is never seen and when I exit the client, the session goes to the same state as the above. It seems that until I reboot the machine, the connections to port 143 on the guest remain in the ESTABLISHED state and I can't get rid of them and any subsequent connections to that port on that host will fail. I can reboot the XP guest VM, but the connections remain in the host and new connections go to the same stuck state. I can telnet to another instance of the same IMAP server running on a different host and have no problems, so it only appears to be a problem with connections to the virtual machine. Any ideas on how I can investigate this further or try to diagnose the problem? How can I get rid of these dead connections without rebooting? Antony