+<dd>The file/directory object is invalid or a null pointer is given. There are some reasons as follows:\r
+<ul>\r
+<li>It has been closed, it has not been opened or it has been collapsed.</li>\r
+<li>It has been invalidated by a voulme mount process. Open objects on the volume are invalidated by voulme mount process.</li>\r
+<li>Physical drive is not ready to work due to a media removal.</li>\r
+</ul>\r
+</dd>\r
+\r