Thanks Nijel, Installing the monitor driver seems to have done the trick. I did look at that earlier, but the install option wasn't available. NB I also found that the host software didn't restart itself, so I had to restart it after changing the settings. That could only be done with direct access to the remote machine. Cheers, John
I sometimes have the same issue when upgrading host's or changing host settings that require restarting the host. It varies from PC to PC & I haven't isolated the cause yet. I use two different remote programs as a precaution & make sure I'm logged in on my secondary program before doing any host upgrade or host restarts. In almost all cases rebooting the host computer will auto-start the host with Windows, if this is your only option I'd recommend scheduling a system restart in Task Scheduler to occur just after you upgrade or restart the host on remote machines.
Just wanted to add my two cents. Starting version 184.108.40.206 we improved the installation process for the Host (you may have noticed that - there's now .exe Host available and also the installation window changed a bit). The purpose of this improvement was to make sure that the Host service restarts guaranteed after the simple update instead of delegating this task to Windows msi which wasn't always reliable in this respect. So if you are updating from 220.127.116.11 to 18.104.22.168 you are already using the new process (unfortunately, it doesn't work retrospectively, i.e. updating from 22.214.171.124 and earlier to 126.96.36.199 won't trigger this mechanism).
Yet, even with that precaution made there may be situations when Host service may not start due to some reasons, such as a/v software activity or security policy (this is true about Windows Server especially). We cannot control these factors though, unfortunately, and it is up to the user/customer to take them into account.