iPhone and iTunes "invalid response received from device"
I'm running a Windows 7 laptop, up to date on patches. I've been running and sync-ing my iPhone successfully for a while now, but it seems since I upgraded to the latest iTunes version (9.1.1), I'm getting the invalid response received error message. I've tried deleting USB ports in Device Manager, resetting the iPhone a couple of times, restarting the laptop a couple of times, uninstalling and reinstalling iTunes, swapping sync cables, and turning off my AV, and it still tells me "invalid response received from device"
Anyone have any ideas that I haven't tried? Thanks.
Pavilion dv6700, Windows 7