sounds like she is being a finicky employee. Are you a superior of hers? Then you just have to deal with her attitude (while of course admonishing her professionally, which it sounds like you did) and let it go. Lot's of employees are never happy no matter what you do. As long as you are doing your job appropriately (which may involve hovering at 'emergency' times such as this one), just let what she says roll off your back.
If you are at her same level (which it doesnt sound like), then I would tend towards a passive strategy for helping her - like other posters have suggested a simple "let me know if you need any other info or clarification" this way you are in the best of both worlds, you are offering her the help she requested, but not "hovering" - I say this only because she sounds like someone that will not be happy no matter what you do, and making her actively seek the help (while making sure she knows it is readily available) is a good strategy for avoiding a "walking on eggshells" behavior around her.
ETA: The only other thign I would suggest is saying something like "There's a new process for when the server goes down, which involves X, are you familiar with it?" This heads off at the pass her "hovering issues" and clearly explains from the get-go why you are standing over her. In this case if she says yes - you have recourse to discuss the issue that she said she was familiar and wasnt, or that she said she was familiar with the process and was (praise her). And if she says no, you then jump in and offer her the info she needs, and you arent 'hovering' Again, if she is still displeased, just let her know that you are doing your job the best way possible (assuming you have looked into ways of dealing with different types of employees work styles, perhaps some advice from a mentor/superior would help you here?) and she is just going to have to find a work-around for the way things are done here.
anyway, I'll stop now...