I have a problem with the internal modem in my iMacG5 (PowerPC, Leopard OS) so I just bought a Zoom usb external modem. However, when I try to connect to the ISP which I used to use before the internal modem problem, the external modem dials and connects but I get "authentication failed" error message so it disconnects before logging onto the internet. Does anyone know how to solve this? I am registered with the ISP so that is not problem.