Bitdefender Internet Security 2012 appears to cause issues (and ultimately be incompatible) with any of the many multiplayer games that use HackShield for anti-hacking security measures. Any game for instance by the huge gaming company Nexon (Mabinogi, Maplestory, Vindictus, Dragon Nest, etc.) will crash with a HackShield related error (often referring to data "hooking") as long as BitDefender is installed and running.
Even if you add the programs and their entire directories to the exceptions list, or even disable the real-time antivirus, firewall, intrusion detection, and privacy settings, it still gets the issue. If you completely uninstall BitDefender however, it begins to function properly again.
Not sure if this is the best place to post this, but figured it would be a good place to start and make people aware.