tedster - 4:16 pm on Sep 4, 2008 (gmt 0)

Yes, it sounds like more than one issue. Going to the last page, or near it, sounds like what we've been calling the -950 penalty [webmasterworld.com]. Very little official word on that from Google. Matt Cutts says it's for over-optimization on that keyword.

Dropping several pages, or even a few positions, could be many things. One might be loss of PageRank for some of your backlinks. Many sites have been losing PR because of paid links that are not coded to stop the passing of PageRank, so Google just penlaizes them. If you're downstream from such a site, then you lose too.

Other reasons for dropping a few pages certainly exist. Most of the time that would show a loss of trust from Google - apparent backlink manipulation is one big cause.

But probably the most important thing you should do immediately is check to see that none of your outbound links point to "bad neighborhoods" - and that includes checking to see if your pages have been hacked and you are now hosting hidden parasite links and you don't know it. Make your backlink check with external software such as Xenu Link Sleuth. Don't trust any back office list of links or visual inspection of your pages.