Comment on Google Panda Update by Bill Wynne.

Google Panda Update I have a site that has been hit during the Google Panda updates and went from #2 to #14 on the Big G.

I have thought about what happened and I wonder if you could comment on the following possibilities.

1. Forum profiles are no longer valuable or even harmful?
2. I have many sites hosted on the same server?
3. I let seolinkvine post articles to my site automatically, duplicate content?
4. There are a lot of backlinks on PR0 and PR1 sites?
5. Allowed content that was not related to the niche?
6. Someone else sabotaged my ranking somehow? Is this possible?

Those are the main ideas I have and would love to get some feedback before my other sites get hit.