13 May 09 12:42 pm
I agree with MartinG. IMO, Google does not ban sites, but they do take the site from natural listing results really fast.
You mentioned about "over optimizing"...what do you mean by this? Do you mean you have very high keyword density on your articles? Follow Mark's technique, 1% KW Density. For a 500 word article have 1 keyword within the 1st 50 words and then spread the next 4 keyword placement every 100 words.
If your articles have a very high keyword density, google bot analyzes it as a spam site so the score probably tends to be negative and then suddenly you cannot find your site on the natural search engine results.
Google is all about relevancy because they want to give their customers the best search experience on the internet. However, they probably are taking it an insult if you over optimize your site by having articles with very high keyword density - they're probably thinking "Oh Darren obviously wrote these articles for the search engine bot and not for our visitors."
I hope you can re-analyze your site so you can get it back to the natural search listings.