We even do paintings and hang inside the brooder. Colorful marbles and other enrichment activities might also help. 
Good information! Yes they squeal.Hi, hope you are enjoying BYC!
Chicks aren't mean at that age... she must be pecking at something she sees, like grooming them? Or possibly the shininess of the eyes.
If you are able to make more of a time out cage inside the same box, that might work well. Or maybe give a little poke of distraction when it starts? Maybe painting or coloring some toilet paper rolls... the chicks REALLY like to peck at little polka dots!
Are the other chicks squealing or responding in a way that seems as though it's hurting them? Or just annoying?
I would try a day time (out of sight) time out instead of night time when they are sleeping. I did have to do this once, though I'm sure it was a bit older. It was effective. And remember they are very young, so it doesn't have to be hours. I think I did 2 sessions, the first was 5 minute and the 2nd was 10-15. Some birds do end up being bullies, but we go with that label yet! 
Squealing should let her know they don't like it. Even if it isn't intentional meanness, it still can be an issue. Injuries could happen.
I love the dirt plug suggestion!
If they already are on shaving and know what their feed is, I love to bring a plug of grass/dirt. It gives them a little grit, a whole of entertainment/enrichment, and it helps them to build immunity to the microbes in your soil while they are still young with higher immunity.
