Partial video transmission in active mode

Help
I have Messenger 7.0 running in Windows Home SP2 through
a ADSL Broadband connection and Norton Security 2005. I
have just done full install of new Logitech Quickcam
Messenger software (Driver 8.4.1.1092) and webcam tests
OK offline for both audio and video in the Messenger
Tuning Wizard. However when online I can see and hear
other party in USA but they can only hear me and there is
no picture of me in local conversation window (either
frozen or black). I have checked that Logitech cam is
showing in Imaging Devices in Device Manager and XP
Firewall off. I did previously try my panasonic DV
camcorder in webcam mode when video picture showed both
ends but the other party couldn't hear me. Any ideas
what the problem is?
.