Disk boot error

[dsh210]

My desktop has stopped functioning correctly on boot and I cannot figure out the reason. If I attempt to boot the system (Windows Vista Ultimate x86) without a Vista or XP disc in the drive, I get a disk boot error where it asks me to insert a system disk and press enter. Inserting a system disk does not fix this error though, it must be booted with the disk already in the drive. I have reinstalled vista and installed XP, but all OS's do the same thing. My boot priority is set to CD-ROM,HDD,USB. Any ideas how I can fix this? It happened to an old 80gb hdd so I got the new 120, but then it started happening here, so I feel like there is something wrong other than the hdd.

My machine:
Asus A8N-SLI w/ AMD X2 4200+
Geforce 6600GT PCI-E
WD Caviar 120GB (OS Drive)
Seagate 250GB (Backup)

 

[eyeCpc]

Your boot order is the problem there. Simply set that to hard drive 1st and disable the rest and you shouldn't have any more problems. When reconfiguring multiple drives seeing stand alone or dual boots of both versions of Windows I end up setting the hard drive only and using the F8 boot device menu for booting from optical. That forces the boot from the hard drive.