Just incase it helps with the solution, my husband and I have both bought new, identical lap tops.
Tonight we both tried to download garmin express using the same internet connection.
It worked for him. It didn't work for me. He uses an forerunner 100. I have a 310xt. I removed the ant chip (which I'donly stuffed in the side so I didn't loose it) , rebooted, removed any garmin software, rebooted, switched off my firewall and none of it helped.
It's very frustrating.