Why am I having problems with my iPhone on my new Windows 7 system?
Certain systems using the Intel P55 chipset running the Windows 7 operating system are currently suffering with an incompatibility issue that is affecting their USB ports. This issue is described in greater detail here.
An update to resolve this issue will likely come from Intel and/or Apple. You can subscribe to this article to receive notification when updates are made.
At this time we can offer only this workaround. Disconnect the iPhone from the PC and reboot the system. Upon restart, all USB should return to normal behavior.
For those users interested in downloading the Intel BIOS update that applies to their P55 motherboard, we recommend you use the Express BIOS Update method: