Amazon.com has become the latest high-profile website to go offline in recent days. Visitors to the US shopping site were greeted with a message saying: "Oops! We're very sorry," alongside a "500 Service Unavailable Error" report. The site returned online about half an hour after the problem was first flagged by users of the news site Reddit. Amazon could not be reached for comment at this time. The firm's UK site was not affected by the issue, however its Canadian home page also showed an error message. It follows Google's two-minute downtime on Friday. That affected the firm's main search page as well as its Gmail email service, YouTube video site and Drive storage product. Analytics firm GoSquared reported the fault caused a 40% dip in worldwide internet traffic. Google has not explained the cause. Microsoft's Outlook.com and the New York Times website have also faced problems... Microsoft blamed a three-day-long disruption to its email product on a failure in its "caching" temporary storage service. It said this "resulted in a flood of traffic that our services did not handle properly". The New York Times has said that an "internal issue" with its servers meant that the newspaper became unavailable for two hours on Wednesday. "It's very unusual to see such a number of high-profile websites all suffering peak-time outages within the course of a few days of each other," said Chris Green, principal technology analyst at the Davies Murphy Group consultancy. "People are going to be very interested to know exactly what the reasons were for the incidents that are still unexplained because the implications are huge: we've seen everything from users being unable to see their email to visitors and third-party retailers who use Amazon's marketplace being unable to buy and sell goods - all happening seemingly with no warning."