Hey! I just got this problem solved. I was downloading the drivers from magellan's site and it wasn't working then I downloaded drivers from another guys site. But it still wouldn't work. I called customer service and he told me to turn my cord around I was screwing it into the back wrong. However, all these years before I knew I could send caches straight to my gps I was charging it with this cord screwed in upside down. As soon as I turned the cord around my computer with Windows Vista recognized my Explorist 400! I was dumb founded and felt stupid, the guy on the phone said don't worry the books never tell you the correct way to attach the thing in the back. I hope your problem is solved as simply as mine was! I'm sorry I don't know which driver did the job, I just believe I googled for EX400 drivers. And found some guy's site or I may have found his site through this forum. Also I use gsak to transfer the info to my gps. Works great.