Problems Restarting

I tried installing XP with bootcamp, and everything was going fine, except I had the wrong disk. (I had the system restore disk and not the installation one.) I shut down the computer, restarted in OS X, and deleted the partition I made for windows.

That was a couple of days ago, and today, when I tried to restart my computer, I got a black screen that said it was unable to find the driver for the platform.

I turned the computer off and started it up again, and held down the option key. There's only the option for my one partition, and once I click on that everything starts up just fine.

What can I do to fix this?