安装中require_once（）问题

下面这个如何解决，先谢了，急


Warning: require_once(D:\www\nav\install/../../inc/common.inc.php) [function.require-once]: failed to open stream: No such file or directory in D:\www\nav\install\index.php on line 2

Fatal error: require_once() [function.require]: Failed opening required 'D:\www\nav\install/../../inc/common.inc.php' (include_path='.;C:\php5\pear') in D:\www\nav\install\index.php on line