Error when cleared cache => Warning fopen: failed to open stream..

I've error msg when I already cleared cached just see

warning: fopen(sites/default/files/filecache/cache_menu/0/01a93d10228633911980ebfe19e36e81--links-primary-links-page-cid-user-1) [function.fopen]: failed to open stream: No such file or directory in /var/www/sites/mysite/mysite.com/subdomains/www/html/sites/all/modules/cacherouter/engines/file.php on line 44.

but when I refresh or I just click another link the error disappear, Is it dangerous ?

Thank in advance