So, I installed Comodo on a Windows Seven Ultimate machine to check out a few unknowns that I had lurking on the box, they were clean.
The next day, the machine refused to connect to any other computer on the network, it needed to be rebooted.
This occurred a couple more times so I uninstalled Comodo because that was the only thing different between the machine always seeing other computers on the network to suddenly not seeing any other computers on the network.
This is despite other machines seeing this computer and still being able to access resources on the machine.
What network setting was changed by Comodo and was not restored when the product was uninstalled because that was not polite.