I've been trying to slog through Quantum Physics for Dummies, but can't even get past the first chapter.  There's a lot of talk of Bras, Kets, and Hilbert spaces, but I feel I'm missing the mathematical underpinnings that would make it understandable.  Can anyone recommend a good book to build up my mathematical foundation for quantum physics?  A textbook or study guide would be fine - I'd want a lot of examples and practice problems.  By the end of this venture, I'd like these concepts to be intuitive to me.
What are the best textbooks to read for the mathematical background you need for modern physics, such as, string theory?  Some subjects off the top of my head that probably need covering:   Differential geometry, Manifolds, etc. Lie groups, Lie algebras and their representation theory. Algebraic topology.
In .NET, what's the best way to prevent multiple instances of an app from running at the same time? And if there's no "best" technique, what are some of the caveats to consider with each solution?