(SOLVED) Zorin OS 9 install problem with nvidea driver

I've been using Zorin OS 6.2 for a while and am very happy with it. I've been trying to install version 9 (on a spare hard disk) on the same machine, but get only a blank screen when the newly installed OS is rebooted. Trying Mint 17 the new install initially comes up in a software emulation mode, allowing me to select the right nvidea driver from a list suggested. A further reboot and all is well.

I suspect that the blank screen in Zorin OS is also due to the correct driver not being automatically selected. Is there a way to force it into this temporary video mode on boot so that the video driver can be selected? The machine is a Toshiba Satellite A100-049 and I had no such problem when I installed 6.2. Sorry if this is an idiot-level enquiry - I'm still a Linux newby.

In the blank screen press ctrl+alt+F1
You will get into tty mode (terminal mode).
Give your name and password.

1. Plug an ethernet cable to get internet.
2. Run the following commands:

sudo add-apt-repository ppa:xorg-edgers/ppa -y
sudo apt-get update
sudo apt-get install nvidia-current

3. Reboot.

Many thanks. That worked perfectly.