Sometimes when I bring up Yawcam (0.3.2, Built 2010-01-02) the console complains that uPNP Port 80 is already open. I am not able to reproduce this, but it has happened multiple times. I suspect that under some condition that I don't understand, the Yawcam software is not closing the uPNP port on the router when it exits.
I changed the default port from 8080 to 80 so that any browser will hit the webcam without having to specify a port number in the address, and I am only using the streaming method.
When the glitch happens I have to reboot the router and the PC. On one occasion I also had the uninstall the software, delete the c:\Program Files\Yawcam directory, reboot and then reinstall Yawcam to get it working again.