I found this in the error logs (maybe I have misplaced something else when installing the IH4):

PHP Warning: constant() [<a href='function.constant'>function.constant</a>]: Couldn't find constant BOX_CONFIGURATION_MY_STORE in /home2/customer/public_html/shop/admn/includes/functions/admin_access.php on line 799

PHP Warning: constant() [<a href='function.constant'>function.constant</a>]: Couldn't find constant BOX_CONFIGURATION_IMAGES in /home2/customer/public_html/shop/admn/includes/functions/admin_access.php on line 799

PHP Warning: constant() [<a href='function.constant'>function.constant</a>]: Couldn't find constant BOX_CONFIGURATION_CUSTOMER_DETAILS in /home2/customer/public_html/shop/admn/includes/functions/admin_access.php on line 799

PHP Warning: constant() [<a href='function.constant'>function.constant</a>]: Couldn't find constant BOX_CONFIGURATION_SHIPPING_PACKAGING in /home2/customer/public_html/shop/admn/includes/functions/admin_access.php on line 799

There is these constants in the language file though, so can't understand what is actually missing but this could be creating the issue, right?