Well, you can do three things - nothing (that's always an option

), you can try "persuading" her by ignoring her (in which case you probably waste time and energy getting really mad at her) or you can be assertive and go and speak to her. Sometimes a little bit of medicine, however unwelcome, is best in the long run.
You could point out that you're aware she is just trying to be helpful, but you don't appreciate her interrupting your conversations, nor having an answer to everything etc etc. When I give criticism, which sometimes I have to, I try to put it in a way in which what I am saying leaves the other person with their dignity. Said politely and calmly it should do the trick. Then perhaps this colleague may come to realise that the world is not in darkness without her contributions.
My two bitz,
Raindance