Google AdSense Down ?

Now the Google AdSense should be in some problem, because I visit all websites with Google AdSense's but no any advertisement displayed, the browser keeping refresh. Finally I saw the following error message:

This Web page is not available.

The web page at http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-xxxxxxx…..

finally I got another error:

This is not first time I meet this. After some while it will be ok. Don’t know why.