here's one thing to check; someone reported getting this error when they renamed their bios file name to "PE.bin" but instead of the file name being "PE.bin" it was "PE.bin.bin" ensure that you do not have a double .bin.bin , if you do, rename the file without adding the .bin
[RN] [biosfilename.bin] [biosfilename]
Then try flashing using
prompt:\atiflash.exe -f -p [adapter number] [biosfilename.bin]
without the brackets
Forgot to mention, for the bios file name, stick with the dos file naming limmit of 8+3
[12345678.123] no more than 8 charactors for the file name and no more than 3 charactors for the extension.
If your motherboard is an agp board, with built in graphics; disable the onboard graphics in the bios, then set init PCI first; use the pci card and a DOS boot disk/thumb/flash drive or DOS boot CD. I think setting init pci first will make the PCI card adapter 0 and your ati/agp card adapter 1, once you have this set, use the atiflash.exe -i to see if your ati card is being detected, then see if it's at adapter 1 position, then your command to flash the ati card will be:
atiflash.exe -f -p 1 [biosfilename]
try flashing with your original bios from there?