Laptop will boot to some usb flash drives but not others

Laptop: HP Compaq 6710b

I can boot from usb just fine with the following usb flash drives:

• Cruzer micro 4GB


• HP 4GB

The flash drive that will not boot:

• Flash Voyager 8GB

To knock out variables I did the following:

• Using Hard Disk Low Level Format Tool
  I performed a low level format


• Full erase with Flash Memory Tookit


• In windows 7 I formated the drive to fat32


• Used USB-Boot-Tester to write to the drive


• Also used uNetbooting with various distros to see if that would make a difference

My guesses on what could be preventing the drive from booting:

• The laptop does not support booting
  to usb flash drives larger than 4GB


• The drive is defective in some way

Answer

have you tried HPUSBFW.EXE (HP USB disk format storage tool)
try FAT16(which it calls FAT I think), FAT32, NTFS
I see it available here
http://codinguniverse.com/files/HPUSBFW.EXE
a slightly newer version is 2MB as oppose to 440KB.

Or, much newer versions of the HP thing. which they call
HP drive key boot utility
about 44MB!

FAT16 is limited to 2GB, so see how that goes..
try FAT32 , and try NTFS..
I haven't tried it in a long while..