Some iPhone users in Asia and Europe complained of malfunctioning alarms on the first working day of 2011, even after Apple reassured users that its phones' built-in clocks will work from Monday.
Bloggers, Facebook and Twitter users complained they missed flights or were late to arrive at work, as the alarm built into Apple's iPhone failed to go off for a third straight day for some users.
"My iPhone alarm didn't work again," user sueannlove from Singapore tweeted on the social networking site. "Time to dig out (the) old school alarm clock."
Similar messages were sent by iPhone users in Britain, Netherlands and other European countries.
The problem was not limited only to the iPhone, with some owners of other Apple products, such as its iPod music players, also complaining of a similar problem with their alarms.
"Apple certainly needs to fix it as soon as possible, but I doubt this will impact sales or reflect negatively on Apple itself," said Gartner analyst Carolina Milanesi.
Apple was not immediately available for comment in Asia and Europe, but it said on January 2 that it was aware of the problem with non-recurring alarms and that the iPhone's alarm will begin functioning normally again on January 3.
Some users said their alarms worked properly on Jan 3.
"This is not a major issue for Apple, but it is sad that they have the same error on vital dates," said John Strand, founder and chief of Danish telecoms consultancy Strand Consult.
The iPhone alarm system failed to recognize changes in daylight savings time in 2010, causing some users to sleep in an hour longer, according to media reports.
The last time Apple was embroiled in publicity problems was in July last year after the launch of the iPhone 4, when reports about bad reception snowballed and forced the company to call a news conference to address the issue, dubbed "antennagate."
This had no visible impact on Apple's sales as the firm sold more than 14 million iPhones in July-September quarter, more than ever before, and is now the world's second largest smartphone manufacturer behind Nokia