I have some reseller hosting and I am running Drupal 7 sites on several different accounts there.

I recently noticed a problem when updating one of them. It happens when I am editing content or changing admin settings. 

 - I go to an admin page - e.g. my.site/admin/people/permissions. 
 - I make a change and hit "Save". 
 - The page submits and reloads. The address
   bar still says my.site/admin/people/permissions, but the page content
   is:

    > Page not found  
    The requested page "/admin/people/permissions" could not be found.

I tried changing .htaccess files, disabling modules, etc, but nothing worked. In the end I did the following:

 - Created a new hosting account on my reseller hosting
 - Installed a fresh copy of drupal-7.58
 - Created a new database

When I repeated the actions above, I got the same results, except this time the error message was the following.

> Forbidden  
You don't have permission to access /drupal-7.58/admin/people/permissions on this server.
> 
Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.

I then checked another account on the same reseller hosting. It's running Drupal 7.54 and showing *Page not found*. 

I didn't have the problem a few weeks ago, so I am wondering if my hosting company has changed something in Apache which is causing this problem (really clutching at straws here).

I am using:

 - Apache 2.2.32 
 - PHP 5.6.30 
 - MySQL 10.0.34-MariaDB

Can anyone help?