Google has apologized for Thursday's glitch, calling it a "traffic jam" that caused many users to experience slow service and service interruptions on Google.com, Gmail and Google News. The sites, as well as Google Docs, AdSense, YouTube, Google Analytics, and Blogger, were unavailable to some users for about an hour.

Specifically, Google said the trouble stemmed from a glitch that routed too much of its traffic through computers in Asia. This glitch translated to 14 percent of its users feeling the pain of an overwhelmed Google server .

"For so many users on PCs, it's the gateway to the Internet," said Greg Sterling, principal analyst at Sterling Market Intelligence. "While technical problems occur from time to time, people essentially expect perfection from Google. In addition to any frustration caused to ordinary users, there's also a big PR cost to downtime for Google because of its visibility."

Google's Outage History

This is hardly the first issue Google has had with reliability. Google experienced a one-two punch in February when a data -center malfunction caused Gmail to go down for hours in conjunction with routine maintenance at a European site.

Google explained that Gmail accounts are typically served out of another data center during maintenance, but some coding issues caused an overload that cascaded from one data center to another for about an hour before Google engineers corrected the issue.

While Google was scrambling to fix the problem, attackers launched phishing campaigns in the Google Talk chat service. When users clicked a link to "check out" a video, they were sent to a site called ViddyHo and asked for their Gmail username and password. Users who gave the information set off a chain reaction that sent a similar message to their online contacts. Google has blacklisted the site and blocked the link.

In response to the issues, Google launched the Google Apps Status Dashboard, a tool that lets customers check the status of services such as Gmail, Google Calendar, Google Talk, Google Docs, Google Sites, and Google Video for business. But it hasn't stopped the outages.

Google Under the Spotlight

Google wasn't immediately available to comment on the persisting issues, but analysts said the frequency of outages is troublesome. "It's clearly a problem for Google to have too many glitches or outages right now," Sterling said. "The company is under increasing scrutiny and pressure from multiple angles because of its search dominance."

Some of that scrutiny is coming from several directions. Trademark owners are taking issue with Google's decision to adjust its trademark policy on AdWords to allow competing companies to create more targeted ads. A Coke ad, for example, can now use the keyword Pepsi so its ads would appear when searchers looked for either soda brand.

Google is also getting unwanted attention from the Federal Trade Commission. The FTC is investigating Google to determine whether the close relationship between Google and Apple violates antitrust laws. Google is also facing ongoing copyright issues with publishers involving its Book Search product.