aristotle - 4:40 pm on Mar 18, 2013 (gmt 0)
plc90210 -- The probable explanation for your problem is really very simple, and if you will read the earlier posts in this thread, you will see that it's already been explained more than once. In summary:
If you create a good website, then it will attract backlinks on its own, without any effort on your part. That's an indication of a quality site.
But if most of the backlinks were created as a result of your own efforts (known as link-building), then they didn't happen "naturally".
Google's algorithm probably found indications that most of your backlinks are the result of link-building, and demoted it for that reason.