I am new here but had a situation simular to what I think he is describing. The server would serve static pages but MySQL, BIND etc.. had failed so it could not connect to the database. At this point I tried to shell into account and could not connect to the IP?
I had several people look at it and we never did find out the cause and no one had seen it before. Had the DC reboot the server and everything was good to go again, may try that to solve your problem.