A Windows update might have removed the existing driver, triggering the "virtual CD" to reappear.
Here’s a helpful report on — a file you may encounter when setting up a Realtek network adapter.
The rtk_nic_driver_installer.sfx file is a legitimate, automated tool designed to help you install networking drivers for Realtek USB ethernet devices when an internet connection is not available. While it might look like a "weird file" or an error, it is generally safe to run to get your internet working. To make sure you're safe, could you tell me:
rtk_nic_driver_installer.sfx /s /v/qn