I've been having the same problem with my Explorist 400. I spent nearly an hour with a Magellan Tech today who determined that there was probably an issue with the data cable or the receiver itself.
I will probably exchange it at Costco this weekend.
I've also had a lot of trouble with the software not playing in the optical drive in my 2 month old notebook. The Tech conceded that they've had some bad discs and will send me a replacement set.
The guy at Magellan went through the whole uninstall, reinstall, troubleshoot process just to be sure that we tried everything and was very patient.
I wasn't too happy that my problem couldn't be resolved, but I was pleasantly surprised at the high level of customer service I received from Magellan. I'm already very happy with the performance of the the Explorist 400.
