HELP - bios doesnt always recognize cd-rom drive

The CD-rom drive in my computer (compaq deskpro) died. So, I replaced it
with a cd-rom drive from a compaq presario. The problem I am having is that
whenever I power on or restart the computer, sometimes, the cd-rom drive is
not recognized by the BIOS. So, I have to sit there and reboot the computer
over and over again until it works and windows xp starts.

When it doesn't work, the bios displays a screen saying "The following
configuartion settings were automatically updated" followed by a list. The
first item on the list is always my hard drive listed as:
[DRIVE] | 20MB | Compaq WDC########
and the second item, which should be my cd-rom drive, will be one of the
following:
1. [DRIVE] | | 60
2. [Other Device] | |
3. [CDROM] | | Compaq SCR-3232

#3 looks correct but even if I save that setting, I get the same behavior.
No matter which of these items comes up, I have not found a sequence of
actions that helps me get correct functioning except for rebooting until the
bios screen does not appear and windows starts. Please help and please
reply to the group. Thank you in advance.
Dave