Try reflashing your BIOS by forcing the Boot Block to perform BIOS update:
1. Copy a known working BIOS image for your board to a floppy and rename it to AMIBOOT.ROM
2. Insert the floppy in your system's floppydrive.
3. Power on the system while holding CTRL+Home
keys. Release the keys when you hear a beep and/or see the floppy light coming on.
4 . Just wait until you hear 4 beeps
. When 4 beeps are heard the reprogramming of the System Block BIOS went succesfull, so then you may restart your system.
Some alternative keys that can be used to force BIOS update (only the System Block will be updated so it's quite safe):
CTRL+Home= restore missing code into system block and clear CMOS when programming went ok.
CTRL+Page Up= restore missing code into system block and clear CMOS or DMI when programming went ok.
CTRL+Page Down= restore missing code into system block and do not clear CMOS and DMI area when programming went ok
Btw: the alternative keys work only with AMIBIOS 7 or higher (so for example an AMI 6.26 BIOS can be only recovered by using CTRL+Home keys).
See the flash recovery guide on my website www.ruisch.tk
for more info.