Can’t Publish All of a Sudden

I’m having an odd problem when trying to publish a new post to my blog. I am able to log-in, create a new post, and edit it. The post also auto-saves. But when I go to hit the button to “Save”, “Save and Continue Editing”, or “Publish”, I get a 403 Forbidden page.

Some more detail:

– The URL for the page within the admin screen is </wp-admin/post.php?action=edit&post=59>
– Hitting “Save” or “Publish” pulls up a URL of </wp-admin/post.php>, and results in a page reading “Forbidden You don’t have permission to access /blog/wp-admin/post.php on this server.”

Any ideas of what could be wrong?