Hi,

It is a configuration error. You need to make sure the /Data folder is writable by the web process user. When pages are created/deleted etc, we clear the site map cache by touching cache dependency files on disk but if the file system permissions are wrong it cannot modify the dependency file therefore it cannot clear the cache. Every 24 hours the application pool recycles and this clears the cache, but you need to correct the file system permissions to make it work correctly.

Hope it helps,

Joe