Using Windows 7 Pro. Both phones are running 4.1.2. So far as I can see, both phones are set up the same way. When I plug my phone into the USB port, my PC recognizes the phone and I am able to see all the files on the phone. I frequently download photos in this manner. When I plug my wife's identical phone into the same PC with the same cable, Windows says it doesn't recognize the device.
I have installed Kies and let it go through its troubleshooting. All it wants to do is reinstall the device drivers, which I have done three times to no avail.
I've read through several forums and apparently it's a common problem, and the fixes seem to be to check debugging, install Airdroid, and one or two others. My phone (which works) does not have debugging checked. I cannot understand why one phone works and the other does not, but clearly it's not the fault of the PC or the cable.
