• Chirp
• Programming Cable Drivers

Before you first connect the radio to the computer, make sure it's set to an unused simplex frequency. Normally, the radio should not transmit while connected to the computer, but if the computer driver is too recent, the radio might go a little rogue and transmit. If that happens, simply turn off the radio and disconnect it from the cable. And check the driver version, which should be v3.2.0.0 NOT more recent. Even if you install the right version, Windows might upgrade it without you noticing at a later point. If this is the case, here's how to backdate the driver:

• Plug in the USB cable (without the radio connected).
• Search for “Device Manager”
• Scroll to Ports (COM & LPT)
• Open “Prolific USB-to-Serial Comms Port (COM3)”¹⁾
• Go to “Driver” tab.
• Driver version needs to be 3.2.0.0
• If driver is more recent:
  • “Uninstall Device”
  • Check “Delete the driver software for this device”
  • Run “Win_Driver_Prolific_3_2_0_0.exe” file to install proper driver (see links at the top of this page).
  • Unplug and replug cable.
  • Verify Driver version.

See this page for more details.