Google blocks World Wide Web
The error lasted about half an hour, but led to a lot of mishap. Marissa Mayer, VP, Search Products & User Experience explained what happened on the official Google blog:
What happened? Very simply, human error. Google flags search results with the message "This site may harm your computer" if the site is known to install malicious software in the background or otherwise surreptitiously. We do this to protect our users against visiting sites that could harm their computers. We maintain a list of such sites through both manual and automated methods. We work with a non-profit called StopBadware.org to come up with criteria for maintaining this list, and to provide simple processes for webmasters to remove their site from the list.
Here's the StopBadware.org explanation.