I've also been having this problem, the workaround I've been using is when you look like you are logged in, log out then re log in and it seems to solve it until it happens again. Hope this helps for now.

To add to Kemp you can also try using a macro

http://qubiqsquare.com/blog/mass-delete-fans-from-your-facebook-page/

Nope

You may find this question from earlier today helpful -

http://moz.com/community/q/weird-back-link-showed-in-moz-crawl

"I have a site where all broken pages are redirected to the homepage. I've been told that it's a bad idea in terms of SEO. I just can't figure out why :)"

"I am not sure what type of site you have but I have a Ecommerce site and when I remove a product I redirect it to the category page it was in."

You've given two different statements.   Best practice to to 301 to the most relevant page.

You can also redirect to similar products.

You are meant to redirect to the closest relevant page if you redirect to the home page it looks like your trying to cheat Google into ranking your home page. It also means the redirect are not given as much value as if you were to redirect to a relevant page.