iPhone, iPad, or iPod is not recognized properly by computer when USB drivers are not installed properly or are out of date

When drivers required by a PC's USB interface are not installed correctly or are out of date, an iPhone, iPad, or iPod connected to this computer may not be recognized properly. One or more of the following may occur: Device does not appear in iTunes Device�cannot be restored in iTunes An exclamation point appears next to the device's entry in Device Manager iPod screen does not display "Do Not Disconnect" screen when connected to the computer�(does not apply to iPhone, iPad, and iPod touch) iPod is not recognized as a disk in My Computer (does not apply to iPhone, iPad, and iPod touch) Products affected iPhone, iPad, iPod touch, and iPod (all models) Microsoft Windows XP Microsoft Windows Vista Microsoft Windows 7

Source: Apple - Support - Most Recent - iPhone