Success! It came to me in a dream, in which I turned on my computer and Dark Avatar started miraculously.
So, this morning, after determining that it was in fact a dream and the game still wasn't working, I was filled with the vigorous spirit of repair. So, I went through a plethora of methods, including disabling my driver entirely. Finally, I stumbled onto the Troubleshoot tab on the Advanced tab of the Display settings. The hardware acceleration was set to None (as recommended for computers that are having graphics issues. However, sliding it around I discovered that one level disabled all DirectDraw and Direct3D accelerations. I turned it up one past that level, and restarted my computer. And, upon starting up the game, it worked! It goes VERY slowly, but with all of the graphics turned down, I believe it will work.
Thanks for all of your help, Kryo, and I hope this helps other people with problems, too.