Play with this REG entry. Sorry I am going from an imcomplete note that had it as a key . . .\Winlogin\RunLoginScriptSync. I think it is like the value entry below though. If you get it right. . . . It will cause the Login script to run before anything else can be done.
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Winlogin]
RunLoginScriptSync=1