When you dial a SP4+ RAS Server from a W9x computer, you receive:

Error 649: You do not have dial-in permission. Change the permissions on the computer you are dialing in to, or contact your network administrator.

When you dial from Windows NT, you receive:

Error 649: The account does not have remote access permission.

If your computer name is System, the subject error occurs.

The only fix is to rename your computer.