The cause of this is incorrect file system permissions. It prevents clearing the SiteMapCache. We use cache dependency files to make it possible to clear items from the cache. When a page is created/deleted/moved we touch this dependency file and it clears the cache. If it fails to modify the file the cache cannot be cleared. The /Data folder and all child folders and files need to be writable by the web process.

You might also try deleting the files from /Data/Sites/1/systemfiles 
This is where cache dependency fies are located, if deleted and file permissions are correct they will be re-created as needed. Sometimes if you move a site from one machine to another the permissions can be funky and deleting them would solve it. 

Hope it helps,

Joe