Check to see that you’re not trying to do a synchronous call cross-site. And if you’re doing PhoneGap chances are the majority of calls you’re doing are cross-site.

$.ajax({
...
"async": false,
...
});

..probably needs to be changed to “true” or removed altogether. If you really need cross-site async JS you may look in to <a href=”http://code.google.com/p/jquery-jsonp/”>Google JSONP</a>.