The following worked for me:

Had the problem after attempting a bios update on a customers' Gigabyte GA-7VA rev.1 using the "@BIOS" windows utility from the manufacturer.

When the PC was rebooted I recieved "BIOS ROM Checksum error
Detecting Floppy drive A media
INSERT SYSTEM DISK AND PRESS ENTER"

Tried several attempts with the DOS boot floppy and the manufacturer flash utility...no go.

Only thing that finally worked was a "open source" utility called "UniFlash" available here:
http://www.uniflash.org/
I setup the autoexec.bat file to run as is described in the download and it worked like a charm. READ the enclosed text files before attempting...As it says, "This is not for the fainted hearted..."

After reading several posts on this and other forums, and how fatal this error can be in many cases, I can't express enough how this utility saved my sanity...what an incredible relief it was.

David Bachman

Classic example of why BIOS updates should be performed from DOS using a bootable floppy rather than from Windows.

Classic example of why BIOS updates should be performed from DOS using a bootable floppy rather than from Windows ... like this.

i_Xp/VistaUser

"Warning:
Because BIOS flashing is potentially risky, if you do not encounter problems using the current version of BIOS, it is recommended that you not flash the BIOS. To flash the BIOS, do it with caution. Inadequate BIOS flashing may result in system malfunction.
"
From gigibyte site.

From a technical point any application can fail. A bios is a memory region to the computer. It cares not the OS installed. The program used to flash is what is failing not the OS.
Dos has had the benefit of being tested much more is all.

I read it wrong and answer it wrong too. So get off my case you peanut.

Over the years, most of the BIOS flashes that I have performed have been from outside of Windows. Although, within the last year few years, I have flashed BIOS' from within Windows at least a dozen times without a disastrous end result.

As hinted by jefro, it is indeed crucial to be extra careful about the flash utility, if the flash is to be performed from within Windows; since some of those flash utilities have been alleged to be buggier than a crack house. It is also important to be sure the wrong BIOS file is not applied regardless of what method is being used to flash the BIOS. As we all know, the information provided by many of the motherboard manufacturers on their website can be ambiguous & many a times flat-out less than accurate & potentially misleading.