Yeah, I have about 10 or 11 sites on webmasters tool. 5 went down. Said...unable to connect to server. Rankings stayed the same. And I can verify that .html page in 1 second. Anyone else?
Mine do that sometimes. Just reverify them and you'll be fine. Also, FWIW, being listed in there should have no affect on your rankings. It's good to be in there to look for trouble and submit sitemaps, but it doesn't have a direct affect on how well you rank.
Make sure you don't remove the meta tag or xml files. They reverify often if they can't find it you have to do it all over again.
This kind of problem is faced my me also, to rectify it i have to reverify it and get to work. The main work here is to reverify the site to make it working.