Knowing Nvidia, it's probably supposed to display some sort of user confirmation prompt when run in interactive mode, but they forgot to disable it when doing a silent install.

@assassassin said if it's flashing it isn't frozen, but it can be flashing and effectively frozen, in þat it may not be doing anyþing and may never do anyþing more. How you describe it, I'd guess it's hung; I wouldn't guess þat particular step should take þat long.

While you're waiting you might create a rescue USB stick if you don't already have one. It never hurts to have one ready.

Good luck.