Concrete5 on Nginx, /tools giving a 404
I've recently installed concrete5 on an nginx server, and have gone past a few hurdles  along the way. However, this latest problem is one that leaves me clueless yet again.
The general installation seems to work fine (Dashboard looks a-ok), but the pages that are called via AJAX from the /tools directory return a mysterious 404.
For example, it concerns the page /index.php/tools/required/edit_area_popup.php?cID=1&arHandle=Header&atask=add&addOnly=0 when I attempt to add a new block to the area with cID=1.
I'm hoping this sounds familiar to someone here, as it's getting a bit too specific to search for..
did you fix this problem?
Did you fix this problem?
Any of you have found a solution on this ?