Installation freeze

Hello Cubase users
I’m installing Cubase on a new machine. For the last c. 90 minutes the installation has simply frozen near the end, installing GrooveAgent, as in the attached screenshot.

But the machine is churning away. See the Task Manager screenshot.

There is no issue with machine capacity: it’s a new 32 GB machine with Raid 0 SSD.
There are no open dialog boxes waiting for confirmation. There are no other open programmes. No USB devices plugged in. I just turned off the Norton antivirus, but still no change.
I also reinstalled Dorico yesterday. I guess if that installation was defective, it might make a difference. But it seems to be running OK.
So now I have cancelled the Cubase installation.
Does anyone have any idea why this might be frozen, or what I should do next?

Thanks to Daniel Spreadbury at Dorico for sorting this one out.