@Shona39 Contact Airbnb ASAP and tell them what this guest is doing. DO NOT let her in to your home.
Why do you say that you can't see her profile and reviews, though? You can- just click on the circle with the letter in it to the left of the Inquiry message. If the guest actually has a profile write-up and reviews, they will appear. I'd never pre-approve someone before checking that out. And BTW, I also get Airbnb alerts in the middle of the night- sometimes from guests in my same time zone, and when I go to read the message, I see they've actually sent it 6 hours earlier- I don't know why the system lags like that.