Windows XP in multi-user environment

We are using Windows XP Professional in a multi-user environment (library). We have a ethernet network and run Novell netware. All patrons are assigned a user name and password for the network. The problem is the local machine (Windows) login. Wehave setup our computers with a generic Windows login that is not password protected. Once students login to the network they frequently re-enter their password on the Windows login screen. This in essence makes the computer dedicated to that user. No one else can login to that machine. A staff member then has to go in as an administrator and delete the password. This can happen three or four times a day! Does anyone have a solution or suggestion?