Well, I tried using the other USB slot and it worked! Phew!
I want to boot a Latitude D600 from a USB thumb drive. The BIOS is version A16  and in Setup I can see the USB Storage Device is on the boot list, however when I hit F12, the USB drive is not on the list of bootable devices. Furthermore, I tried disabling all boot devices except the USB Storage Device in Setup. When I do this it tells me there are no bootable devices. One peculiar thing about this machine is that it is dual boot Windows/Linux. Could this be blocking access to the USB device as a boot device? Any ideas welcome.  Cindy
Need to boot Latitude D600 from USB drive