DNS secondary server rejecting update queries

[TMcB]

Hi all
Looking for some DNS advice.
Last week we had to rebuild our secondary DNS server and created it on W2003. our primary server still runs on W2000.

We also have other servers on the network which use load balancing, and as part of this need to update DNS regulary.
These have been failing since we rebuilt our server.
The error messages are :

0S ANY A (delete)
5M IN A 172.25.81.9
;; Querying server (# 1) address = 172.25.49.1
;; new DG socket
server rejected query:

Would anyone have any ideas?
Thanks so much