Are you sure that you have Aging and Scavenging correctly configured?
Check this out...
http://support.microsoft.com/?id=296116
Coraleigh Miller
"NZSchoolTech" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>I had a situation where a reverse lookup of a computer gave the wrong IP
>address and I found a stale PTR record in the DNS reverse lookup zone that
>had a date on it of 8 June, almost 6 weeks ago. The properties said it is
>expected to delete the stale record but this record is still listed in the
>DNS.
>
> Is there some reason why this has not been purged as the reverse lookup
> has caused a program running on the server to get the IP address which has
> long since been reallocated to another computer by DHCP.