hello i hope this will work. don't use WSAAsyncSelect() probably your window might be missing some messages posted by mfc socket framework (This will happen) use WSAEventSelect() by creating one more thread. send notification messages to your main window by using SendMessage() function. it will work perfectly. Possibly one more reason is Socket abort operation notification will take at most 2 msi cylcles ( 1 msi is 2 minutes). this is tcp ip implementation bye yln