I have 2 Harddisks installed on Primary IDE. The AOpen CDwriter and ASUS DVD writer install on Seceondary IDE. The system worked perfectly.

Recently I bought a WESTERN DIGITAL SATA2 250GB (WD2500) and had it install on the First SATA and I had already set the jumper to SATA1 mode at the back of the harddisk. When I checked the BIOS, the Harddisk name was visible at the First SATA then I saved and ReBOOTed. The System said
Bad BIOS checksum. Starting BIOS Recovery...
Checking for floppy...
Floppy not found!
(After several times I then put the ASUS CD that came with the M/B )
Checking for CD-ROM
CD-ROM found.
Reading file "P4P800-X.ROM". Completed.
Error! ROMID is not compatible with existing BIOS ROMID.


I tried to reboot the system again and again and Removed the SATA2 Harddisk until the ASUS Logo appeared on the screen and i had to set the time and date of the system again in the BIOS menu.

Using WinXP, I used the ASUSLiveupdate to copy the current BIOS from the Mainboard to a Floppy disk and rename the file to "P4P800-X.rom"

Then I tried to reboot from the WindowsXP for 5 times (Without the SATA2 installed) No Problem!

I then connected the SATA2 Harddisk and turn on the system and the same problem happened.
With the ASUS BISOCrashFree2 function, I use the floppy disk containing the system P4P800-X.rom and it said i have to turn off and on the system.(After the flshing and programming) I did it and The same problem happened(Bad BIOS checksum)

The Problem now is In many cases including with or without SATA2 HD installed and using the ASUS-CDROM or my floppy disk. The "Bad BIOS checksum" always appeared. I dont know what to do now. I'm so depressed Pls HELP

SYSTEM Information:
BIOS version 1009
1.8 GHz Intel
Winfast A170 Gforce4MX (AGP4X)
1 GBs RAM (256,256,512)
120GBs Seagate, 40 GBs Maxtor, ASUS DVD writer, AOpen CDWriter
Juli@ Audio card
and the recently bought WesternDigital 250GBs SATA2 HD (WD2500)