Ok - so this is the OP.
1) First - Yamaha Steinberg is aware that Windows 10 1803 trashed their driver. I asked them if they were working with Microsoft to make sure that this does not happen on the 'next' update and he said they were. Not sure if that has any bearing on Version 1803.
2) I tried to uninstall the driver through Windows
Control Panel>Device Manager>Sound, video and game controllers>Steinberg UR824: Driver tab: Uninstall Device" and did not click the 'delete software' box. This is not the correct way to do this and led to (3).
(3) When I tried to use the Steinberg Tools for UR824 to reinstall driver software, it wouldn't let me select any software. So now driverless. After a somewhat long chat session with Steinberg USA, they gave me a support number to call and the person there was very helpful.
4) What we did was:
a) Windows Control Panel>Program and Features
Select Yamaha Steinberg USB Driver
Uninstall
b) Go to
https://www.steinberg.net/en/support/downloads.html
Click pull down on 'Downloads Hardware'
at bottom of list is:
Yamaha Steinberg USB Driver
- select and download that
- unzip and install
Now UR824 working OK.
Protools not hanging.