Looks to me like you need a router.
A portscan means that an outside computer is trying to see if you have any ports that will accept connections.
This usually means it is trying to see if your computer has any known vulnerabilities in network software so it can install a trojan or compromise your machine.
You can easily lose connections when you have a machine tying up your network by trying to open connections on every possible port. This is most probably not ZenFire's problem.
Get a router that does NAT and you won't have outside computers contacting your machine.
- Curtis