I have the exact same problem with a Compaq Presario F750US laptop. I've reinstalled the bios, installed a replacement DVD drive and even tried removing the hard drive while booting into the bios, but still no dice.
Essentially my laptop is now worthless, because it doesn't have a CD-Rom or an option in the bios to boot from USB CD-ROM.
The only thing I can figure happened, is that a virus infected the firmware of the DVD Drive?
My next step will be to find a firmware for the DVD Drive and if that doesn't work... I will remove anything I can use as spare parts and throw it against the wall and then drive my car over whatever is left!!!