Interesting, no haven't seen that before with the Cloner, but have seen it in other cases. This almost always means that you don't have write permissions on the directory that PHP is configured to use as its session save path (or it just doesn't exist). Usually this is /tmp but different hosts have different default setups.
A couple possibilities:
1) Make sure that /tmp exists under your main root (probably same level as public_html) and that the owner has write permissions. Permissions should probably be 755.
2) And/or you might have to check your PHP ini or check with your host as to where the session save path is configured and make sure that PHP has permissions to write to it.
Hope that gets you there! Let us know!