How to evolve the role of my admin?

Hi guys,

I'm a 28-year old CIO for a healthcare company in Mexico and started listening to manager-tools' podcasts a few weeks ago. I'm enjoying them like crazy, I wish there was a way to put them all in a memory stick to get them all in my head since there's lots of valuable information and too little time to process it all!

I thought of using this forum since there's one thing that's been rolling my mind and I'd like to get your feedback on it:

I've been in this company for a year now but my executive assistant has been here for over 7 years. She's a very efficient person and is great at managing budget and following up with other areas on pending items. However, she has some bad  communication habits:

1. She comes to me with things like:
- "I've been asking John to get me that information but he doesn't want to send it because, according to him, he's really busy". And I really don't know how to react since I don't want to know about every bump she encounters in achieving the result we've agreed for a particular task or project.
- "I don't want to get into other people's business but I think that John and Clark are having problems beacuse John told me he's tired of Clark's attitude", my response is "and what do you expect me to do with this information?" - "Oh nothing, I just thought you should know".
 

2. She also holds grudges with some people (and people to her since she's strict with expense reports before she hands them over to me for approval, etc) and gets easily pulled into gossip.

I really want to give her more responsability and delegate some activities (like email, follow-ups, etc) but I'm having a hard time figuring out how to approach the issues to change her behavior (really change it) and thus be able to trust her with more sensitive things and evolve her role.

Any thoughts?

Thanks!
Rodrigo