USB Keyboard Not Working?

Issue(s):

I currently own a MacBook Pro 15" (no Retina Display) and I like to play some pretty fun games on it. Knowing that Apple keyboards are bad for gaming (due to the fragile keys) I bought a Dynex Keyboard to use for my gaming. I have been using this keyboard for about 3 months and it seemed to work fine with my MacBook. I started to play Assassins Creed II last night and the keyboard worked fine for a while. Then, the top row of letter keys (Q, W, E, R, T, Y, etc.) weren't responding.
I opened up my System Preferences and noticed that my MacBook was not recognizing my USB keyboard –note that the other times it recognized it automatically.
I then clicked on "Change Keyboard Type..." and figured out I could have my MacBook recognize the USB keyboard manually. I tried this and it worked a few times, but now, it's just not working any of the times I try it.
I would like to know how I could fix this problem.

Additional Information:

- OS X 10.8.3

- 2.3 GHz Intel Core i7
- NOT RETINA DISPLAY
- DYNEX Wired Keyboard; Model No.: DX-WKBDSL