I'm amazed that the nanny is still there.
Your first thread about her was 9th May, when you were given similar advice as on this thread.
It is now nearly two weeks later, she is still there, and you still have the same problems.
She's been working for you for less than a year.
You say you've given her warnings.
Why is she still there?
I'm really confused, because the image you paint of her is not great, but yet you say she is "generally a nice girl", and you "don't want to ruin the poor girls career by sacking her".
So she's a crap nanny that you don't want to sack for being a crap nanny, in case the fact that she is a crap nanny stops her getting other jobs, where she will continue to be a crap nanny?
I wouldn't have looking after my children for another minute, frankly. And not because of the nudity issue, but because she clearly doesn't respect her employer, so I wouldn't trust her to care for the children properly.