After having a problem with Comodo Firewall Pro, I decide to revert back to Outpost Firewall. Comodo is by far the best free firewall I've ever use; but I get frequent BSODs with Comodo while using uTorrent. Apparently the problem arise from the firewall driver Comodo implement in their firewall: inspect.sys. Anyway, Agnitum Outpost Firewall is easy to use (for me at least, because I'm an ex-Outpost user, before trying out Comodo.) and no BSODs since then. The only lowdown on Outpost is the resource usage, Comodo is light-weight while Outpost use a little more CPU resource.