In order to run X-Win32 flash you need a USB drive with a valid serial number. Although recommended, Serial numbers are optional with USB devices.
To check if you have a conforming USB drive download and run USBDeview. Find your device, and look if it contains a string in the Serial Number column
TIP: Select the Options Menu > Uncheck Display Disconnected Devices to narrow your search
USBDeview is a utility program which gives information on USB devices which have been connected to your system.
For more information