My friend of the opposite sex thinks I want her - I dont - what do I say?

I think all you can do now is behave like the professional you are. You dont owe this woman anything from the personal point of view, and she does owe you a professional performance at work. Disregard what you see as the elephant in the room. What she may mistakenly believe about you is her own problem, and it is not up to you to explain anything. Tell her, as an employee, which she is, that she needs to pull her weight and get organized for the presentation, or it will have professional and career repercussions. Tell her you value her abilities, but that you cant overlook the fact that she is jeopardising the whole project by not working to the high standards she is capable of, and that she needs to apply herself immediately to rectifying this. It's not a personal issue, it's a professional one. People have to behave professionally regardless of what's going on in their own minds and private lives, and learning this is something she has to do.