Author: Jamie Welch, Senior Editor

Facebook users have been complaining about problems at the social media site. Users in the U.S. and other countries reported problems beginning Saturday morning. Some could not log in, and the site was unusually slow and glitchy for others. Users in London, Bangkok and Mexico City reported problems. Many used Twitter to complain. Facebook spokesman Matt Hicks said the company is working to restore access as quickly as possible. Without giving a specific number, said it was a “small percentage of users” who had problems accessing Facebook, their friends' profiles or specific site features because of an isolated server problem. Facebook, which has more than 400 million users, has generally avoided such hiccups. Twitter has had bigger problems. Last August, hackers shut down the short messaging service for several hours.  Facebook also had problems, but was never shut down...