Just curious, after she stopped at the crossbar... did you ever make her go over it? Or did you hop off and then set up the poles? Whenever a horse stops at a fence I always make them go over it at least once more. Esp a crossbar. A crossbar they can just step over. Or hop over from a stand still. It's understandable a loud noise scared her, but regardless she needs to go over the fence and realize that it's still not going to eat her alive.
It's hard to tell what's going on because I'm not there to see it... but, and maybe I'm wrong, but I have a feeling that after the initial spook you were a little nervous to it and your body language was unintentionally telling her not to jump. All the things we do when we're nervous to a fence -staring down at it (this is a biggie), getting tense, sitting back right before, etc- basically affirm to your horse that the poles ARE scary and that they either shouldn't or can't jump over it. Why did she stop to the crossbar in the first place? Does she stop regularly? My initial feeling, again could be wrong, is that either you were a little nervous because you hadn't jumped in a while and she felt it or she has stopped before and the poles making a scary noise was just another thing to stop at. Is there a chance I'm right at all or am I just making things up?
Either way... one of the best things I've ever heard a trainer say about jumping (esp a looky horse) is: "throw your heart over it (the fence), and catch it on the other side". It's basically just fancy way to say "just do it" but I love the sound of it and there have been many times I've had to tell myself, "throw your heart over it!!" This trainer also told me (after my horse did a huge stop) "ride your horse like he's good horse". So your horse stops. Keep going and make him go over it. Don't keep anticipating he's going to stop or he will.
Generally one scary crossbar does not ruin your horse's jumping career. (esp if he's already trained to jump!) I have a feeling you are going to be just fine! Be bold for your horse, make him do it, and "throw your heart over it and catch it on the other side!"