Apple customers say devices with the new iOS 5 operating system are still suffering from weak battery life, even after the company issued a software update meant to fix the malfunction.

Users has posted on Apple's message boards complains that the software update delivered yesterday hasn't corrected the flaw. Apple said that it's looking into the matter.

"The recent iOS software update addressed many of the battery issues that some customers experienced on their iOS5 devices," Apple spokeswoman Trudy Muller said. "We continue to investigate a few remaining issues."

Among many complains, iPhone 4S users say that that battery life has gotten worse since the software update, while others complained that the battery loses 10 percent of its power each hour.

Furthermore, users are also reporting a new problems that were apparently introduced by the 5.0.1 update. Some users aren't getting a proper contact name displayed when receiving a call, despite the name and number appearing in a user's contact list. Users are also complaining of microphone problems, WiFi signal issues, and difficulty connecting to cell networks.

Apple also announced a replacment program for the first generation iPod nanos due to faulty batteries. Apple has determined that, in "very rare" cases, the battery in the iPod nano (1st generation) may overheat and pose a safety risk. Affected iPod nanos were sold between September 2005 and December 2006, the company said.

Apple has traced the issue to a single battery supplier that produced batteries with a manufacturing defect.

The company recommends users stop using their iPod nano (1st gen) and order a replacement unit via the web.