Ajax error on navigation menu

On a fresh theme install I had set up a link with use-ajax class on main menu.
The ajax call works fine, until the following scenario is tested:
1. click on a non-ajax link.
2. while the page is loading click on the ajax link.
3.
Get the drupal popup
"An AJAX HTTP request terminated abnormally.
Debugging information follows.
Path: /ajax/node/add/ajax/page
StatusText: error
ResponseText:
ReadyState: 0"

coming from ajax.js:
Drupal.ajax.prototype.error = function (response, uri) {
alert(Drupal.ajaxError(response, uri)); ...