Hi,
Make sure that your USB Stick is formatted in FAT32 on a PC not MAC and, if possible use one under 4GB in size. Copy the BIOS update file to the USB Stick.
Disable Floppy Drives in BIOS
Shutdown the PC and plug the USB Stick into one of the USB ports on the motherboard's back panel.
Restart the PC with the USB plugged in and hit the "END" key to go straight into QFlash the USB stick will probably show up as an HDD.
Try that and let us know if you still have problems.