I have a 2002 IS300 SportCross with the factory Sat Nav. When I first bought it, the Sat Nav was a bit patchy, frequently saying it couldn't read the disc, so I replaced it with one from Satnavi.com. This worked perfectly for a while, now I get a message saying there is no disc present. Also, occasionally, if I turn on the Sat Nav, it works for a few seconds before the message pops up again. Do I need a new DVD unit? Is it a case of unplugging the old one and reconnecting a replacement? Sorry for lengthy post, I did a quick search and couldn't really come up with anything, but I'd assume this is a relatively common problem? Thanks for any assistance.