It was a rough day for technology: the United States' biggest airline, its oldest stock exchange, and its most prominent business newspaper all suffered technology problems that upended service for parts of the day.

Government officials said that it did not appear that the incidents were related, or the result of sabotage, counter to an endless stream of jokes and conspiracy theories posted on Facebook and Twitter - and even the suspicions of FBI director James Comey.

"In my business, you don't love coincidences," Comey told Congress today. "But it does appear that there is not a cyber intrusion involved."

First a "router issue" at United Airlines suspended all of the company's flights for nearly two hours, leading to 800 flight delays and 60 cancellations.

Then at 11.32 a "technical problem" at the New York Stock Exchange halted trading.

In the midst of that, the Wall Street Journal's website, WSJ.com, had "technical difficulties" that sent readers to a temporary site while the paper worked to fix the problem.

"The problem is humans can't keep up with all the technology they have created," said Avivah Litan, an analyst at Gartner. "It's becoming unmanageable by the human brain. Our best hope may be that computers eventually will become smart enough to maintain themselves."

Technology makes life easier and the economy more efficient, allowing for nearly instantaneous flow of information and communication and for remote control of far-flung operations. Until it fails.

And technology problems like today's that temporarily knock out vital services and conveniences of modern life are likely to become more common as computers and other electronic devices increasingly connect together over the Internet.

For United, it was the second major technical issue in two months. On June 2 the airline had to halt all takeoffs in the US because of what it described as computer automation issues.

The length of today's outages is also disconcerting, said Litan.

It took the New York Stock Exchange until 3.10 pm - just over three and a half hours - to resume trading. "I think everyone needs to assume technology is going to go down sometimes, but you should be resilient enough to quickly recover from the outage within a half hour, if not a few minutes," Litan said.

Still, being deprived of technology for a few hours is a reminder that it is still clearly better than the alternative.

"When you've got six or seven billion shares a day (trading) I'm not sure you've got any other choice," said Larry Tabb, founder and chief executive of the Tabb Group, a financial research firm that focuses on market structure and trading.

"I can't image going back to paper tickets and floor trading. If Google goes down are you going to have a bunch of people with encyclopedias looking up answers for people? The cat is out of the bag."