I just downloaded the latest Comodo firewall pro today. It installed but after that, it would not allow me to connect my desktop to the internet. My wireless laptop using the same internet provider through a router was working fine. Also, I would not find the Comdo firewall in Windows Add/Remove program.
Try to do a repair connection by right clicking on the 2 computers in the taskbar and choosing repair.
Have a look at the posts concerning dhcp release.