What's so wrong with progressivism?

I know lately Glenn Beck has been touting the evils of progressivism, even claiming it's the ideology of the Nazis, but it just doesn't make sense to me. Isn't the progressive movement responsible for some of the crucial advances in our society? Women's suffrage, ending segregation, anti-discrimination laws, rights for disabled people, etc., etc, they're all progressive ideologies. What is so frightening about this?