DHCP Addresses

We have DHCP installed on Windows NT4 server and has been running for a year or so with no problems. However now we are unable to get any clients to receive a previously used and now unneeded IP address. We have more than enough addresses available but it doesn’t allow this. The Subnet mask is properly set to 255.255.254.0 considering we have more than 255 machines needing IP addresses. Netbeui works fine and Static addressing of old IP addresses work fine too.

Any help would be greatly appreciated.

Cheers