I got the USB problem on my lumia 830 when i hard reset my phone after updating to the latest build (10586.29). Nokia Software Updater 4.3.2 worked fine, i am now back to 8.1. Thx guys, this was the only page i found to have a solution. I won't update to windows phone 10 again until the final version. My battery now lasts much longer!!! Although i can't listen to my .flac songs now, it's not a good deal.