Htaccess gives 403 error on back office

[Lilybos]

Whenever PS is creating a new htaccess file, I do lose access at the back office and the frontend shop.

Both gives me a "You don't have permission to access /index.php on this server."

When I manually delete this htaccess file, I can again access both back office and front end

 

I'm trying Prestashop 1.5.3 on localhost (Apache) on Mac OSX 1.8.2.

 

Thanks for your help.