dont wack her on the nose..

if she is playing hard and bites you, it isnt good..

But if thats the case then I have a pretty good solution for ya, because my great dane went though this too..

First of all put peanut butter on the top on your hand, and let maggie lick it, let her know that it is ok to lick not bite, and she will get rewarded to lick not bite...

if she bites then yell loud in a stern voice *ouch* and turn away from Maggie and ignor her for 2 min, then get her to sit and then tell her she is a good girl after she sits..

try that, tell me if it works for you.