Dell Dimension not recognising SATA hard disc as a numbered device in BIOS order

Hello. I have a Dell Dimension C521 that recently had its internal battery go flat. A consequence of this is that the system's boot sequence got in a muddle, so it began trying to boot from the floppy disk drive (which it doesn't have). I went into the BIOS settings and tried to reorder the boot sequence. However the SATA hard disc, is present in the list but not a numbered device. Therefore if I put the hard disc at the top of the list, and the CD drive second, it looks like this:

SATA Hard Drive

1 CD-ROM Drive

There is a note in the BIOS boot configuration menu stating that the system will boot up numbered devices in order. Therefore even with the SATA hard drive first in the list, it will be ignored at power on and go straight to the cd-rom drive. I cannot find a way to assign the SATA Hard Drive a number so it is recognised at boot.

The tempoary workaround I'm using so I can use the system is to interrupt at boot screen and manually select to boot from SATA hard disc rather than CD-ROM. However this is not ideal. Any suggestions would be really appreciated.

Many thanks,

James.