Steve,
Two simple long shots to consider.  Is your BIOS checking all disks for bootable sectors?
You might try eliminating D: from the boot sequence search, I leave mine A:, C:.
Less probably you have virus scan, BIOS built-in probably, enabled and it is
telling you it did not scan drive D: with this cryptic error message.
Tom Turak
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        Hi.
>
> Steve Dias wrote:

> > Problem: Every time we reboot, we get an error message "fixed drive has no
> > boot sector". Pressing F1 to continue, machine will boot to Win95 on C:,
> > both drives are recognized and useable in Windows.

        Having a whole second disk with an extended partition is common, to
avoid DOS letter assignment misorder. However, if there is a primary partition
on the second disk, it is irrelevant if it is marked active or not: normal
booting is from the active partition on the first disk; however, recall that
modern bios give you options to boot from the second, third or fourth disk
(badly indicated as D, E or F), so probably it is necessary to have an
active partition to use this feature (bios probably fetches the MBR and gives
control to it).

Javier Vizcaino. Ability Electronics. [log in to unmask]