Hey I have a question for you guys, rather important.. do either of you have google webmaster tools?
If you do, this is suuuuuuuuuuuuch a longshot, but can you go there and lemmie know if your robots.txt and sitemap both look fine?
It dawns on me now that I recently had a similar problem, but caught it really fast, some folks tht didn't catch it as quickly.. are also being deindexed..
Hate to give false hope though :/ .. mine had to do with my host, which was hostgator.
If there's a problem with either either your sitemap and/or your robots.txt but you can still go directly to their addys.. might be a like problem that we can actually fix..
I'm a WAHM (work at Home Mom), I primarily write gambling content like poker reviews, and gambling news, as of right now I'm writing about the WSOPE. You could say I'm a gambling Affiliate Webmaster I review poker portals, and I am against the US Gambling ban!