cross-browser file access problem - javascript / geoxml3 /google maps

Short version: code  works fine in Firefox, in chrome/internet explorer i get an error in console 'cannot open file' when trying to load the kml (generated from a php script)

since it works in FF, I don't think my code has a problem, but maybe it requires an addition
 to make it work in other browsers? hmm... im not an expert, any advice to fix the code problem is welcome,
many thanks!

using geoxml3 library
google maps apiv3

reference links:
usage of geoxml lib:  http://erskinelabs.com/cartography-javascript/

files attached to re-create my setup,
demo link: http://unosat-dev.web.cern.ch/unosat-dev/smcsv2/delkmltest.html
geoxml3.js
ProjectedOverlay.js
delkmltest.html