DHCP Assigning Duplicate Addresses

[Chris \(Net Admin\)]

Here's a clip from the logfiles from my company's DHCP
server indicating the problem I'm having (heavily edited
to remove MAC, subnet scheme, etc):

15,08/05/04,08:29:34,NACK,192.168.0.140,PC1.company.com,MA
C_ADDRESS_01 (User #1 - DHCP denies his IP from the
previous day)

10,08/05/04,08:29:40,Assign,192.168.0.50,
PC1.company.com,MAC_ADDRESS_01 (User #1's computer
aquires new IP)

15,08/05/04,08:38:59,NACK,10.0.0.2,
PC2.company.com,MAC_ADDRESS_02 (User #2 - DHCP denies his
DHCP from home network)

10,08/05/04,08:39:08,Assign,192.168.0.50,
PC2.company.com, MAC_ADDRESS_02 (User #2's computer
aquires the IP assigned to User #1 minutes before)

13,08/05/04,08:39:08,Conflict,192.168.0.50,BAD_ADDRESS,
(self-explanatory)

13,08/05/04,08:39:08,Conflict,192.168.0.50,BAD_ADDRESS,
(self-explanatory)

10,08/05/04,08:39:19,Assign,192.168.0.51,PC2.company.com,
MAC_ADDRESS_02 (User #2 gets a new IP because the old one
conflicts)

I'm at a complete loss as to why this is occuring. Any
help would be greatly appreciated.

- Chris

P.S. Apologies for not supplying my email address, but
there are plenty of unscrupulous perusers out there.

 

[Chris \(Net Admin\)]

Anyone? No one's had issues where DHCP would assign a
just-issues IP address to a different MAC only a couple
minutes later?

Note: So far it only appears to occur when Dell D600
Latitude laptops are involved, which is likely a big
clue, but Dell claims no knowledge of known issues.