Just when you thought it was safe to turn on your iPhone ... Antennagate may be over, but complaints are now rolling in from iPhone 3G users who downloaded the latest Apple mobile operating system.

There are reports that upgrading the iPhone 3G and iPhone 3GS to iOS 4 causes the phone to drag and the battery to run out more quickly. Apple has said it is investigating the issue, according to a report in The Wall Street Journal.

"My I-phone 3G was running perfectly fine, till I updated to OS 4, it's been slower than the slowest, and even turns itself off at anytime, during browsing and even during calls. I updated to 4.0.1 only to improve things a little bit. Still the problems persist," wrote a user from India who calls himself I-Phone 4.0.1 bugs. "Am cursing myself why I updated it."

Worldwide Complaints

The problem isn't confined to Asia. Users in the United States are reporting the same issues. Some say the iPhone 3GS now "stutters." Others say the iPod capabilities on the phone are "completely busted." Still others report the updated iPhones won't go to the home screen and take 30 seconds to respond to various commands.

One forum complainer named "Savvytraveller" said his apps are crashing or just freezing after the upgrade to iOS 4.0.1. This same users reports the handset is getting hot. The complaints go on and on, giving Apple another headache after the iPhone 4 case giveaway just eased the last one.

Indeed, this isn't what Apple expected when it touted iOS 4, the newest version of the iPhone mobile operating system with the much-anticipated multitasking. Many iPhone 3GS users upgraded to tap into the multitasking capabilities, which promise to let users switch between apps while preserving battery life.

iOS 4 also offers a new Folders capability that...