Installing iOS 8 on iPhone 4S via Windows 7, hung up on "Plug into iTunes" image. "Run Diagnostics" crashes, too, btw.

OS: Windows 7

iTunes 12.1.2.27

iPhone 4s - A1387

Trying to install new iOS (8, I'm pretty sure?)

iTunes prompted to install newest OS for the phone, successfully created a backup/sync, shut off the phone, and now it's stuck waiting to be recognized by iTunes to get the new OS installed.

When the phone is plugged into the computer, Windows gives the "Device Detected" sound but it doesn't register as a camera or storage device anymore. Meaning I'm not sure where the device is supposed to be located in Device Manager.

iTunes does NOT show that the device is detected.

I've updated iTunes to 12.1.2.27

Restarted the computer several times, as well as the phone.

Tried another USB slot

Tried another computer (Windows), and while it DID register in iTunes, it failed to Restore OR Update

Tried Help > Run Diagnostics, but that crashes iTunes.