martinibuster - 3:40 pm on Nov 20, 2012 (gmt 0)

If it's not your site content then it's something you're overlooking and assuming is ok, something like, for example, links from sites you own or a preponderance of links from search engine friendly directories, something that ordinarily would seem innocent but under a hand check won't pass muster. Even something like having some link swaps/reciprocals of a certain number might do it, particularly if they are on pages with URLs like linkswapper01546, linkswapper01547.htm...

Good luck, it must be very frustrating for you. Hope something turns up.