I found the problem:

Believe it or not, it was related to includes/configure.php

I manually set the parameters inside the config file and here is the wrong code:

Code:
define('DIR_WS_CATALOG', '/');
define('DIR_WS_HTTPS_CATALOG', '/');
When I removed the forward slashes the problem disappeared. I noticed that the url was localhost/shop//page......

Just thought I post my error here just in case someone else has the same problem.

Goshawk