Thanks GreatMarko, that helps. Why on earth take the program binary out of %programfiles% where binaries are supposed to be?? I can understand putting configuration files in %appdata% as these are likely to be different per user, but not the binary executable!!. This doesn't work for me, or many others I would wager, as I want to run the sync as a normal non-administrator. The %appdata% location is user-specific - C:\Users\Paul\AppData\Roaming\BitTorrent Sync - if I was to have to run the installer as an administrator, it would go into the Admin account's AppData location, and I'd still not find it using a normal account. The previous arrangement made much more sense! Anyway, thanks to your hint, I found the btsync.exe executable in the AppData\Roaming\BitTorrent Sync location, and ran it manually (the installer could apparently put it in there successfully, but couldn't execute it seems) and once triggered manually it then completed the rest of the installation, including setting itself up to run on boot. I now have 2.1.4 running on both machines. Thanks again Marko.