Whether ports are open or not has nothing to do with this particular error. Sure, opening them will improve download speeds, but they're not necessary for the torrent (or any client program in general) to work or start up and make initial connections. Have you even tried the simplest option of uninstalling and reinstalling the software to wipe it's settings to default, then rebooting? As you said, it used to work, so either it's (or some software firewall) has been misconfigured lately, or you installed something recently that's causing this.