Green question marks can occur with the following USB device classes: Keyboards, mice, and Universal Serial Bus (USB) hubs. USB printers usually do not directly exhibit this issue, and thus are not affected by green question marks. This indicates that an exact (device-specific) driver is not available, and that a compatible driver has been installed. This new feature was implemented so that you can use the device, even if an exact driver is not available. Even if a device contains a green question mark, most if not all of the features will function properly.