Comment Boxes Are Black

Why are the comment boxes black and can't be read? I have a user that when she opens any excel documents, the comment boxes all appear black. Even when she tries to create a new comment - it is black as well.

She can right click and choose format, colour, fill and change the colour so she can edit. But she has to do this for each comment. Some of her documents have a lot of comments and she does not want to select each one. All her features are set the same as mine so I don't understand.

Help Please,

Cathy