Novel and Windows 2000 terminal server

We are running novel as our main server that stores files and dose logins. We are trying to run windows 2000 terminal server so as the machines can run applications and windows in a multi session enviroment. This workes fine but when a client is running a terminal version of windows from the server, they then log into the novel server so as they can access files, they can read a write to there home directories and all the drives are mapped as normal. the problem is that they have full access tothe novel server when they are in a terminal session. why is this and what can we do to stop it.