I was testing using NHibernate in ways that I never did before*, and the test kept failing. Each time I would fix one thing, and another part would break. It wasn't very obvious how to make it work. I had a guy watch over my shoulder while I worked throught the kinks of the problem. After the test failed repeatedly for the 10th time or so he just muttered something about "never making it work right" and walked away to do something else.
To me, TDD is all about failures. I know that I need to do something only when I get a failing test. And the failing test kept pointing me to this error and that error, and I kept researching and fxing the errors. Eventually I had enough understanding of what I was trying to do and how NHibernate was trying to accomplish it that I could get it to work (perfectly). All in all, it took about 30-40 minutes of trying.
I am not upset to see failing tests, they are the best sign that I have that something is wrong.
This is a Failing Test.
There are many other tests, but this one is a Failing Test.
My Failing Test directs me where I need to be going.
* Highly complex schema with some indirection thrown in to add to the mix.