DHCP: unable to add a reservation

[Oliver]

Something's got wrong by adding a new DHCP reservation:
- the reservation is currently not shown
- neither the IP address nor the MAC address is shown in view “Active Leases”
- when I try to repeat the reservation, I get the error “An error occurred
while accessing the DHCP database. Look at the DHCP server event log for more
information on this error.
- on DHCP server event log is nothing related logged.
- the client gets no address by booting or ipconfig /renew.
- event log of the client has logged first, that the requested IP address is
currently in use by another client (warning). After rebooting a lot of
DHCPNACK’s are logged.
- I did a backup of the DHCP database and edited it with a HEX-Editor. A
search for the MAC address is successful.
- I did already a reconcile and a restart of the DHCP service.

Conclusion: I assume that a corrupt entry of the reservation is stored
somewhere in the database. But I’m not able to manage it.

Server is a W2K3 SP1 server.

How can I resolve this problem?

Thanks, Oliver