Method 1: Select the first USB port to connect the USB adapter. Normally this USB port can detect the boot up devices. (Check the BIOS to make sure this port is in the bootup list if there is a setting in the computer BIOS.
Method 2: Reload the USB adapter driver before connect the USB adapter to the computer so that the computer can detect the device after you installed the driver.
Method 3: Some devices can not be detected by Vista when the computer is booting up because of the device driver. Try different versions of the driver if it is available.
Method 4: If there is no other version drivers, go to the Vista Start button, Settings, Taskbar and Start Manu, Start Manu tap, select classic and add the adapter to the start manu.