When I connect my iPhone 3GS to my PC, iTunes "freezes": Activity Monitor shows iTunes as "Not Responding". The iPhone indicates that it is being charged, and otherwise seems normal. When I disconnect the iPhone, iTunes immediately returns to normal operation. Connect again, and instant freeze again. I have rebooted the PC, uninstalled iTunes and reinstalled it and have reset the iPhone. No help. Everything worked fine yesterday. I haven't installed software or changed anything since the last time I synced. iPhone 3GS is running version 3.1.2(7D11). It is jailbroken.