nsupdate communication failed

[Christophe]

Hi,I use nsupdate to update each minute some textfields
representingstatus of several kind of information.
The update performs correctly but some times, (once every ten ortwenty
times) nsupdate outputs an error like :

Communication with XX.XX.XX.XX#53 failed: operation canceled could not
talk to specified name server

I have create a file with commands and repeat execution with debug -D
options until I get error.
Content of file is :server XX.XX.XX.XX
update delete {fullyqualifieddomainname} TXT
update add {fullyqualifieddomainname} TXT "data"
send
quit

Then the output is :
setup_system()
reset_system()
user_interaction()
get_next_command()
get_next_command()
evaluate_update()
update_addordelete()
get_next_command()
evaluate_update()
update_addordelete()
get_next_command()
start_update()
recvsoa()
; Communication with XX.XX.XX.XX#53 failed: operation canceled could
not talk to specified name server

Has anybody an idea on what can cause this behaviour ?
Server logs receive no request at this time
Systems are as following :
dns server : win2k3 sp1, running cisco network registrar 6.1.2.1
nsupdate client: same machine with nsupdate.exe, all dll needed and
vcredist installed

As as use the same machine, destination address is the real ip address
I have tryed to set source and destination address as 127.0.0.1 and
the problem persists.

Thanks in advance for your help.