Problems with DHCPDECLINE with no IP Conflicts

[JoelSeph]

I am running bind v 3.0.2 for a statically assigned dhcp configuration.
 I have a php-mysql interface that I use to build the dhcpd config file
and restart the dhcpd process.  Host MAC addresses are assigned
addresses with the fixed address directive in dhcpd.conf.  I am running
into a lot of DHCPDECLINE entries in the log files.  Hosts are
continuously rejecting and re-requesting addresses.

Upon changing addresses, the hosts appear to be fine, but some end up
with the same problem after a few days.  Upon checking for ARP entries
after changing the addresses, I don't see another MAC using the
address, and the ARP entry will remain with the proper user's MAC until
it times out and is automatically flushed by our border router.

I first suspected that the problem was being causesd by
/var/db/dhcpd.leases being empty, but then after researching I found
that fixed address assignments are not stored in the leases file, which
makes sense.  I understand that DHCPDECLINE messages originate from the
host thinking the address is already in use..  What would cause this?