I'm very sorry to hear that you encountered some problems after installing some of our software. We're doing all that we can to investigate the issue you've mentioned, though we've also seen reports of this problem occurring with other software made by 3rd parties, it doesn't appear to just be our software that will occasionally do this on High Sierra.
If anyone else experiences this issue, please try following these steps:
- Boot into Recovery Mode on your Mac (hold CMD + R during boot up)
- Select 'Disk Utility' from the list of options
- Select your start up disk in the left sidebar
- Click 'First Aid' at the top of the screen, then select 'Repair Disk'
- Once that completes, try booting the computer normally
If you continue to have issues after that please contact us directly and we'll do all that we can to get you up and running: https://support.focusrite.com/hc/en-gb/requests/new
Jack // Focusrite Technical Support