DOS 6.1 boots and will do DOS things except when Hard Disk is involved. Executing FDISK results in a blank blue screen with a blinking curser in upper left corner. Nothing on Hard Disk, just trying to install a system (any system) on it. Booting from Windows 98 CD causes same result. Reloaded BIOS sucessfully from ASUS, but no change in result with FDISK. HARD DISK, CD-RAM and LEGACY FLOPPY all show in BIOS SETUP screens. Can read from all except HD. Any clues appreciated.