2. Once. I found her attractive, and I think she was at least willing to become interested in me. (Of course, I'm a clueless male geek, so I easily could have been mistaken.)
3. Her equal.
So, yeah, it hasn't happened to me very much. But the time it did, I did what I felt I had to to make sure that nothing happened. (What did I do? I sent one message that I wasn't going to play, and I asked a male co-worker that I trusted to hold me accountable for what I did and thought about her. It was enough.)