Port forwarding is for the outside to be forwarded to the inside of the network so Blackarm is right about that and it's a big risk to open ports to your network therefore he wrote the lines in bold. And I don't se any that offending in his first post giving the rest to react as the following.
So don't set Port Forwarding when you guys are trying to connect to the outside world, NAT is connecting everything for you already!
I fully agree that port forwarding should be done sparingly, but the security risk related to it is very overrated.
A forwarded port that doesn't have an application listening to it is basicly the same as a port that isn't forwarded.
The main problem with port forwarding is that it gives outsiders a hint of what programs you might have on your computer.
For example, if i were to figure out that you have port 6112 forwarded then i'd know that you probably have a blizzard game installed.
And that you probably host games or use their torrent based updater.
Now, if one of those games/applications listening to that port had a severe bug then i could exploit to comprimise the system when and only when the game were running.
Now, considering the launcher only is open a few minutes every day it gives you quite a tricky task if you were trying to exploit a bug in it.
In general, not using an addblocker, visiting sites you'r not sure about, clicking shortened URLs (such as TinyURL) and downloading files from other places then the source (for example the FTBBETAA folder from other places then creeperhost) poses a MUCH greater security risk.
But yes, as you mention should port forwarding only be needed if you'r trying to host something, not if you'r trying to reach something.
I could easily be wrong so if i've missunderstood anything about port forwarding then please feel free to correct me.
As mentioned before i think it's most likely that the problem is caused by one of the two anti virus programs running.
Or that there are two seperate anti virus programs running on the same system which can cause all kinds of wierd conflicts.