js exception 问题

[Exception... "Component is not available" nsresult: "0x80040111 (NS_ERROR_NOT_AVAILABLE)" location: "JS frame :: file:///D:/Program%20Files/Mozilla%20Firefox/components/nsSessionStore.js :: sss_saveState :: line 1914" data: no]用firefox的firebug看页面的信息时, 提示了这么一条, 这是firefox的错误还是我的js错误啊? 请详细说下, 谢谢.