For testing purposes you may need to perform local ajax calls against the filesystem. If you are running the pages throw a web server, everything should work as normal, but if you are accessing the local filesystem directly you may need to adjust the security settings in your browser.
Firefox
- In the address bar type in "about:config"
- Set the "Security.fileuri.strict_origin_policy" to false
( see: http://kb.mozillazine.org/Security.fileuri.strict_origin_policy )
Chrome
- Load chrome with the "--allow-file-access-from-files" command line flag set
( see: http://www.chromium.org/developers/how-tos/run-chromium-with-flags )