Going for the ankle shoes

Question
We have an English lab that will be 2 in Sept.  When some of my children's friends come over to play, sometimes Roxie will go after their shoes, and in the midst of it knock them down.  Obviously because she doesn't stop, they are afraid of her.  She's not biting them, just trying to show who's in charge I guess.  This has been going on for about a year.

We got her when she was 9 weeks old.  

What can I do to stop this behavior?

Answer
It sounds like she is just untrained and has no manners, and not that she is aggressive.  I would suggest taking her to classes with a good positive trainer.  If you are in the US, try these sites to find one:
www.clickerteachers.net
www.trulydogfriendly.com