Site Dropped from Google

We have had the #1 site on Google for our search phrase for over 2 years. Sometime in Janurary it dropped out of Google, could anyone tell me why this would happen? When we type our URL in Google the page displays the following information: Sorry, no information is available for the URL sullivancountyrealestate.com Any help would be appreciated.

This might be for one of a few reasons:

1. Your server was down while Google was attempting to spider your site. The dance was on January 26th, so it would seem as though you would have been removed then. You should get back into the index if this is the case (so long as your server stays online).

2. You were spamming in some way and were removed. In this case, I'm not sure you'll get back in.

3. You changed server and Google did not resolve to the new name.

What I see from looking at your site is that your home page is not ranked by Google but some of your inner pages are. When looking at your keywords you have Sullivan in almost every phrase I count it something like 18 times and that's not counting what you have in the body text. I'm not sure the exact count it should be..... it changes, but I know you are way over, could be considered spaming. And what search did you use? " Sullivan county real estate?" You really need to rework your page. You'll get a better rank if you don't slam the word. It will pick up "Sullivan county Real Estate, Recreation, restaurants, Dining, Events, weather, New York Catskills, travel, woodstock, hunting" and so on but even that is too many targeted keywords. Try using different pages for different keywords and come on is weather really related to real-estate? Drop it !it's diluting your true targets. look at your competition for the keywords you seek and check their source and what they are doing? Sometimes it's just luck they are up there. I'm surprised you rated that high for so long except I hear Google doesn't pay attention to meta tags but other engines do. And Google does look at your overall words both hidden and in the body and they base things on weight and count. Could be they just felt you were spaming the word Sullivan and dropped the page.
Then again....they could just be nuts ... or is it me?

I agree with what Sward says. Additionally... it can help to add a Site Map page, but include a short description of each page, not just a list of pages; that way Google is more likely to treat your SiteMap as content. Link all your pages to your Site map page.
I notice the inward links on your home page from http://www.delawarecountyrealestate.net/ and http://www.orangecountyrealestateguide.com/
These are not going to help your link popularity because all 3 sites appear to be on the same server: it will help to have each on a different server/IP