i believe ray436 is correct...
on earlier compaqs, and up until they got a clue, they use to put the CMOS information on a proprietary partition... if this drive was low level formatted, or if the partition was removed with FDISK, then you will not be able to make changes...
good news... you can download and setup a 2 to 3 floppy set (depending on the model) and boot from it... you can then manage the CMOS settings...
bad news... unless you feel like completely reloading, your gonna have to deal with the floppies until the next time you reload... the floppys have the capability of recreating this partition on a blank hard drive...
advantage... keep the floppies in a safe place, and only YOU will have access to make the advanced CMOS changes...