I just wanted to put this here because I had the same issues and did everything and nothing fixed it.
Tonight I resolved the issue for good.
Before you run through the vive setup, close out of Steam. Navigate to you're Steam application short cut and right click, RUN AS ADMINISTRATOR. Likely somewhere along the long line of Steam app updates, the Devs changed permission requirements, or it's something to do with the way your OS is configured for permissions. Whatever the source, I don't care. I finally won my fight. I'll also have you know that none of the 3 college degrees I have helped me resolve this issue, so don't post silly ego centric things like that, it's been annoying reading all the BS troubleshooting forums with similar posts.
For windows 10 users, go to installed applications under settings, search Vive, uninstall the software, uninstall the driver (don't run the repair your wasting your time), don't need to mess w the diagnostic file. Close Steam if you have it configured to auto boot upon system start-up. Then Run Steam as Admin and follow the Vive setup.exe advice. ESPECIALLY IF THE VIVE WAS WORKING THEN MYSTERIOUSLY STOPPED.
If you're having to swap USB ports and it magically works one day then doesn't the next, no offense comp sci degree holders, but that's noobish lol and you should know why. Get a mobo that's compatible if this is your issue and verify your processor is compatible too. You'll know what I mean if you've done your research. It's sad how many hours I've sunk into trouble shooting this POS, but it's a pretty good device despite hardware/software issues.
I'm leaving a lengthy post for all the sad folks out there still searching, hopefully your Google character search leads you here.
Best
Jeremy M
