Razer Blackwidow Mercury Edition

The only game I play is World of Warcraft and since switching to this keyboard from another Razer product I've noticed that when using the keyboard keys to move I'll end up still moving when no longer depressing any key. I returned my first keyboard and got the same product because of this issue, but since it's duplicated I'm wondering if it's a software setting or something, even though I can't find such a setting. Any help would be greatly appreciated. I've also been noticing keys not actuating when I'm typing, but I'm attributing that to differences between keyboards and getting used to the actuation point of this keyboard.