Uncaught SyntaxError: Unexpected token when trying to open media browser popup [#1857552]

Hi,

I'm unable to open media popup browsers (both file field and wysiwyg button) and so cannot select any images to upload and/or insert. In console i can see the following error:

Uncaught SyntaxError: Unexpected token <

in the file:

/sites/default/files/js/js_-le50342DDyc_6GhljKFfeeYPPIWL_yeZir2Yd01PxI.js

on line 899, which starts with <!DOCTYPE HTML. I've copied from line 884 until the end of the file and pasted it below, if that helps. It looks like the js isn't closing before the html starts.

      $('.media-edit-link', this).bind('click', function () {
        var fid = fidField.val();
        if (fid) {
          Drupal.media.popups.mediaFieldEditor(fid, function (r) { alert(r); });
        }
        return false;
      });

    });
  }
};

})(jQuery);
;
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>401 Authorization Required</title>
</head><body>
<h1>Authorization Required</h1>
<p>This server could not verify that you
are authorized to access the document
requested.  Either you supplied the wrong
credentials (e.g., bad password), or your
browser doesn't understand how to supply
the credentials required.</p>
<p>Additionally, a 401 Authorization Required
error was encountered while trying to use an ErrorDocument to handle the request.</p>
</body></html>
;

Has anyone seen anything like this before, or at least has idea what might be causing it? I may well have installed a few modules since i last knew it was working, looking through the log it looks like they may have been: Drupal for Facebook, Twitter, Facebook Page Rules, Devel, and FB oAuth. I have since disabled all of those and it still doesn't work.

I've tried changing the theme in case that had something to do with it but it happens with Bartik too.

Help...