Yay! I solved it! Turned out it was a glitch in my theme and not WordPress itself. Anybody else using Atahualpa might want to check it out:
Go to Appearance.
Go to Atahualpa Theme Options.
Click on “Export/Import settings”
Click the button towards the bottom of the screen labeled “Delete ‘bfa_ata4′”.
Reload your blog.
Yay!
A way to test to see if this is the problem is to try loading a different theme–even a default one–to see if your blog still comes up. That’s how I figured it out.