Logon error with script

Hi!
I have a simple logon script, that maps a network drive. I got the following
error on login:
"An extended error has occurred"
and the drive is not mapped.

This script was working fine for over a year, until we made the last updates
for W2003 server.

In policy the following setting is enabled
"Always wati for the network at computer startup and logon"
to ensure the network is up.

The script works when it is executed by doubleclick the file.

Any Help or ideas

Thansk a lot
Jörg