TORONTO - The second BlackBerry outage in less than a week disrupted service for millions of users on two continents, frustrating people so reliant on the messaging devices that they peck at their keyboards all day and keep the gadgets on their nightstands while they sleep.

When the problems began Tuesday night, Twitter and other online forums were peppered with laments about the failure of a gadget that has been dubbed the "CrackBerry" because it can be so addictive.

"If my BlackBerry is down, everything is down," said Sarah Whalen, 22, of New York. She said her BlackBerry did not resume working until yesterday afternoon.

The company behind the service, Canada's Research in Motion Ltd., blamed a software upgrade for the problem, which it said was confined to North and South America.

RIM said BlackBerry users were unable to send or receive e-mails and instant messages. Many users also found the Internet inaccessible, though many could still make phone calls. RIM would not say how long the outage lasted or exactly how many users were affected.

The glitch comes after another outage last Thursday and at least three breakdowns in 2008.

The latest problems are happening at an especially bad time for RIM, which is facing tough competition in the market it helped pioneer.

"One of RIM's big advantages is that it's perceived as a reliable device," said Duncan Stewart, director of research and analysis at DSam Consulting. "To lose the advantage of reliability would, in fact, be a very big deal for this company."

RIM has sold more than 75 million BlackBerrys since the gadget was launched 10 years ago. It now counts 36 million subscribers around the globe and ranks second in the worldwide market for advanced "smartphones," with a 21 percent share, behind Nokia Corp.'s 39 percent, according to market research firm Gartner Inc.

BlackBerrys are especially popular in occupations heavily dependent on messaging - among lawyers and business executives, for instance.