When the logon script runs fine I notice that the z: is mapped to the logonserver\netlogon. (when it doesn't work I don't see the z: or any other network drive mapped)

The part of the logonscript that maps the netlogon directory is
:OS_IS_NT
Set LOGONSCRIPTPATH=%LOGONSERVER%\NETLOGON

Apparently all the domain controllers have the same files on them.

I'll have to check for the update.kix to see if I can get the code for it. Do you have any suggestions on what I should look for in the update.kix? (you mentioned that kix uses z: "This driveletter is used by KIX in the initial running of the script.")

Thanks,
T.