I found the problem is because my BIOS is very strict about MBR compatibility. Now I can boot in DOS mode. The flash drive need to be formated as a Win98 Startup disk using HP USB disk storage format tools. Unetbootin menu is booting from USB but won't install BAMT.
If I use Windows or Linux diskimager it is deleting the good MBR. I tried converting BAMT .img to .iso and it is not booting with Unetbootin.
Is it possible to boot BAMT from a Win98 DOS command prompt? Maybe there is a way to burn the image and keep the working MBR?
If the working MBR is deleted, the flash drive is not recognized at all by the BIOS.
Here are some info if someone happen to buy the same nightmare:
GB's BIOS will only boot USBs formatted to FAT-32, conforming to normal MBR bootloader. I've seen this before, and surmised that the 'stick-maker' was formatting in ReiserFile, or one of the EXT 'flavors', but no one ever followed up to confirm or deny... Also, if it's putting the bootloader into its own partition - won't work! http://www.tomshardware.com/forum/274441-30-tutorial-making-bootable-flash-drive
In the BIOS, on the "Integrated Peripherals" page, the "USB Storage Function" item must be enabled (which should be the default) to allow USB booting...
I've put a little work into a 'GB USB booting tutorial', and frankly, I'd just go ahead and finish it up for you, but I really don't want to reboot the several times it will take me to 'firm up' procedural details, and take the BIOS/boot pictures for the post - just noticed VAIL finally went 'public beta', so will be downloading for likely twenty-six hours or so There's likely enough there to test a 'raw DOS boot', just to see if your hardware (especially the USB stick itself) will do it...
Fixed. Here is a brief summary. Since my ubuntu live usb sticks (2gb kingston and 8gb sandisk sd/usb reader - fat32, created in ubuntu 10.04) would not boot this board even though they would boot my ga-ep45-ud3p, I decided to try bilbat's suggestion with the HP usb boot program. I created the win98 boot disk on the kingston 2gb stick without reformatting. It booted right up. Next, I used windows version of unetbootin to write the ubuntu live cd to the kingston disk. This fired right up and completed the install.http://www.tomshardware.com/forum/274723-30-880gma-ud2h-fails-boot