This error cropped up while writing some Methods to modify existing Active Directory user accounts. This error occurs if you try to use DirectoryEntry.CommitChanges to update the CN attribute of an entry object. If you search around a little you'll find the short answer is to use the DirectoryEntry.Rename method for changing the name. However, it's important to note that the Rename method needs the format "CN=Joe Smith". For example.
objEntry.Rename("CN=" & strFirstName & " " & strLastName)