These things are maddening - but great fun.
Essentially the problem isn't about the money: it is whether you will do what the Super-Intelligent Being predicts you will do, so you're having to guess on which option she predicts you will choose. Since this Super-Intelligent Being is exactly that: she hasn't been known to be wrong so she must be able to accurately assess the motivation of every person taking the test, therefore in my case her prediction must involve some detailed knowledge about me and my circumstances.
1. This isn't really about money: it is about the Super-Intelligent Being predicting my thinking.
2. If I choose wrongly then I'm losing nothing: I'm just not gaining anything.
3. The Super-Intelligent Being should know enough about me to know that in these circumstances I'd happily forego the prospect of £1,000 for the certainty of £1,000,000.
4. Therefore, I choose Box B and hurry off the the bank to deposit my £1,000,000.
After all, if I don't get the dosh by choosing Box B then it means the Super-Intelligent Being predicted wrongly for the first time ever!