Thank you, thank you, thank you! All I had to do was right-click Steam and run as Administrator. It worked great after that! It had been a few months since I used the VIve, so some updates had to be installed. After that, it wouldn't work. I "determined" that my Vive must be broken because I tried setting it up on a different, brand new, gaming PC while also bypassing the linkbox and it still gave me the dreaded Error 108. I decided to order a lightly used replacement HMD via eBay and, to my disappointment, ran into Error 108 with that unit, as well. Running Steam as Administrator fixed the issue in no time. HTC needs to plaster this fix on their home page because running into this error on after installing on a brand new computer means it must be a very common show stopping issue with a super easy fix.