Did you use AFUDOS.EXE as your flash utility?
(ASUS EZ Flash won't cut it)
(There's also a Version 1010.003 [beta] if you click on the Beta button...haven't found a discription of all the changes, but so far it's working fine here!)
You'll need a basic DOS-based BOOT floppy, no Autoexec.bat or Config.sys necessary. Copy AFUDOS.EXE to the floppy. Download the BIOS version you want to Flash. Rename it (for simplicity) P4C800.ROM and copy it to the floppy.
Make sure you have enough space on the floppy to save your OLD version. (about 450 Kb for your present version)
REBOOT, enter BIOS and set up your floppy as your first boot device. Save your changes, and boot to DOS.
At the > prompt, type afudos /ip4c800.rom /op4c800.old
This will save your old Bios (.old) to the floppy, and Flash the new one to ROM.
Reboot, go to Bios and restore your old BOOT sequence (or just remove the floppy), exit and save changes, and you now are running with the new version.