warning: unlink(C:\www\tmp/cache_menu_lock) [function.unlink]: Permission denied

This is happening in Windows (XP SP3), not linux.

$Id: Cache.php,v 1.1.2.14 2009/09/05 13:03:25 slantview Exp $

warning: unlink(C:\www\tmp/cache_menu_lock) [function.unlink]: Permission denied in C:\www\sites\all\modules\cacherouter\Cache.php on line 124

Cache Router Config

$conf['cacherouter'] = array(
  'default' => array(
   'engine' => 'apc',
   'server' => array(),
   'shared' => TRUE,
   'prefix' => '',
   'path' => 'files/filecache',
   'static' => FALSE,
   'fast_cache' => TRUE,
   'shared' => TRUE,
  ),
  'cache_form' => array(
  'engine' => 'db',
  ),
);

Digging further I found out this line is causing problem -> Cache.php

Line : 61

$this->lock = $this->lock_dir . '/' . $this->prefix . $this->name .'_lock';

In windows if I replace the '/' with '\\' the issue is solved. Is there an OS check required for this line ?