I am the Site Admin. I have tried to edit a block that I have created a week ago but, when I click on Preview or Submit the changes, I receive the following page:

Forbidden

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

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

This happens when I create a new block also, I even logged out closed the browser and started over.

Thanks