Google Webmaster says site has severe health problems

I'm having a strange problem with my main site. Google webmaster has started reporting that the site has "Severe health problems" because a page is being blocked from the crawlers. The page is


Which is the wordpress admin area and is meant to be dropped. I had 1st place for a 27,000 search and a few 2nd page for bigger searches. All have since dropped out of the rankings completely and are not visible in the top 100. Ive slowly started getting them to reappear. I think the dropped rankings and the "severe health" notice are related because i have not seen a drop in other rankings i have.

Any idea how to fix this or has anybody seen this before?

so is your site not being indexed anymore? or what exactly is the problem..? might be sandbox'd.

No the site still appears in the rankings and has not been sandboxed. The rankings just dropped severly once i started seeing that message. Im slowly getting some traction again, but how do i fix it. I dont want google to index the admin page and none of my other sites with the same setup have this problem.

Remove the admin page from your sitemap??

depending on how long this has been going on I might just give it a lil time. with regards to the admin page im pretty sure that depends on your cms.

again sorry for the lack of actual help.

-At0m

Havent the foggiest but i have to note that im using the sitemap provided by Wordpress SEO by Yoast. I have another 30 sites and none of them have this problem. Its really strange.

So your admin is blocked in the robots.txt file? Have you double checked using WMT that the googlebot is able to see and interpret your robot file?
I've only seen this message once, and it is because I have a domain which is entirely blocked from googles spiders, so my robots just reads User-agent: *
Disallow: /

This is what my robots.txt says:

Which to my mind is the basic stuff.