I have had the identical issue with Diver's Diary and my Icon HD Net Ready, but it's not even an issue of different computers or USB configuration. Diver's Diary does not work in OS X. But if you run Windows in a virtual machine on the same Mac, Mares Windows dive log works just fine. So it's clear that it's a software issue, not a hardware issue. I have had several communications with Mares techs, who initially thought that the problem was hardware related and limited to the Icon. I told them of my experience, and also told them that I've been using Macdive which, after some beta testing, released a new version that does allow the Icon to communicate with the Mac OS. The said they would look into that. At this point I don't know when, or if, Mares will solve this problem.