Forbidden You don't have permission to access /user.php on this server.

Hello,

Out of no where I am getting the following error upon attempting to login to my efiction site:

Forbidden

You don't have permission to access /user.php on this server.

Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.

I've changed nothing at all in probably more than a year. Any idea on what might be causing it or how I can fix it? I've read that this is often a permissions issue, but nothing there has changed either. Pretty sure I'm running 3.5.5, but can't actually log in to verify that.

Thank you.