Start, Control panel, Windows Firewall, Exceptions, make sure all the apps you want to run are checked! (add them with the add program if not) including ports etc via that, in fact, I never use the windows firewall.... but thats probably your problem! Ever since I've had a router, nearly 2 years now, I've ran Every single port open, and never had a problem (also I make sure all of my apps can run through the firewall in windows) and its good! Give it a shot if you havent already! oh and dont forget, you could have to reformat already!  the joys of computers, I know!

Cheers, Gunny