blend27 - 10:19 pm on May 3, 2010 (gmt 0)
I just went thru this issue with one of the sites I took over to manage, for my friend.
Internal linking was the Issue, Duplicate content was served via 4 different URIs.
New Site, 8 month old, somehow the DARN original CMS Developer desided that is was OK to do so.
Removed the links to Dupe Content, redirected Via 301 none homepage links back to the homepage, BOOM, 2 weeks back in BIZ!