why/where the error “Permission denied for to call method Location.toString”

Question

EDIT: I\'ve added clarifications in response to a comment; where it\'s possible and meaningful, those added carifications are in italic font style.

Answer 1

Per my comment, try disabling extensions (safe mode) and check Firebug's XHR tab if you haven't already.

Answer 2

This may not be the case with you at all, however be aware that firebug will display error messages in your console if you open-up another window and browse to a site that has these calls. In short, these errors may not be related to your page at all.