ASUS's site says this:
Notice:
If you are going to upgrade BIOS from BIOS version 1001.A (and earlier) for CUSL2 or 1002.A
(and earlier) for CUSL2-M, please make sure the following item in the BIOS setup menu is set
at [PCI/AGP] before updating the BIOS.
Advanced -> PCI Configuration -> VGA BIOS Sequence
In case the system is unable to start up properly after performing BIOS upgrade, please
remove all the add-on VGA adapters from the system and start up the system with the onboard
AGP graphics controller or clear CMOS. The add-on VGA adapters then can be installed after loading the
setup default from the BIOS setup menu.