Okay, but here's the thing. Your conclusion was that it happened because you're black. I think that's a hasty conclusion.
Not only are you black, but also you were dealing with a big, probably disorganized company. The larger the organization, the more moronic its hiring practices can be, and the more they can accidentally poop on candidates. I'm white, have a CS PhD, and have experienced similar things.
Also, even if you did actually run into racism, I suspect it's rarer than you expect. Running a software company is so difficult that one generally wants the most productive, high-quality software developers available. There's rarely enough wiggle room to accommodate personal bigotry. Most of us care a lot more about having our company succeed so we can be wealthy, than we do about skin color.
Also, you had one bad job interview experience, right out of school, and you quit the entire profession? I know that's discouraging, but seriously, you need to grow some backbone.