A day after the latest iPhone software became available, some users are complaining about new problems with their phones like a shorter battery life and random shutdowns.

Apple on Wednesday introduced version 3.1 of the iPhone software in iTunes, where it became available for phone users to download.

By Thursday, people began complaining on an Apple support forum and Twitter about problems.

"I updated last night without a hitch," one user going by the name MarkGoBlue wrote on the forum. "But now I get random complete shut downs of the phone." After a hard reboot, he can get the phone back to normal.

Four people commented that they had the same issue, with one person saying that the phone has shut down five times since downloading the new software.

Other users say that the battery life of the phone seems much shorter since making the update. One says that he upgraded the phone and charged the battery to 100 percent. After going to bed and waking up six hours later, the battery life was at 55 percent, he said. During that time the phone didn't receive any calls, and Wi-Fi and Bluetooth were turned off.

Some customers are also saying that after making the update, all their podcasts seem to show up in random order, rather than by date.

Some corporate users have also started having trouble synching their Exchange e-mail since the 3.1 upgrade.

Scattered reports of problems have popped up during the past couple of iPhone software updates, typically related to the volume of people trying to download the update at once.

Apple did not immediately reply to a request for comment about the reported issues.