I'm having some issues with Windows 7 Home Premium 64 bit. Zone Alarm is blocking my application's response to a UDP M-SEARCH. Zone Alarm is allowing Windows Media Player to respond to the same M-SEARCH. If I shutdown Zone Alarm, my application's responses to the UDP M-SEARCH go out just fine. I'm pretty sure I saw this on 64 bit Vista also. My XP machine doesn't have this issue. Any help would be appreciated.