Google said that for nearly an hour on Saturday, users got an erroneous message when they did searches on many sites, saying, "This site may harm your computer."
The problem began at 9:30 a.m. ET and ended at 10:25 a.m. ET "What happened? Very simply, human error," the company said on its blog. Google said it flags search results with the message when a site is known to install malicious software. Instead, many other sites were affected.
A detailed explanation is available at /http://googleblog.blogspot.com