Some iPhone owners in Europe and around Asia continue to have trouble with the alarm clock built into the mobile phone.
The problem came to light on the first day of the new year, but iPhone maker Apple had said the built-in clocks would work from Monday.
Even though some users report still having problems, industry analysts said it is unlikely to impact sales or reflect negatively on Apple itself.
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.
The iPhone alarm system failed to recognise changes in daylight savings time in 2010, causing some users to sleep in an hour longer, according to media reports.
The last time Apple suffered 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.
This had no visible effect 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.