problem with EnvUpdate()

[mactable]

it is an example of my very simple script

opt("TrayIconDebug",1)
EnvUpdate()

i could run this script on other machines, but my machine cannot, when i run this script, tray icon appears but only show "AutoIt - XXX.au3" and no debug information, this script seems freeze and i have to end "autoit3.exe" in task manager to exit.

do anyone have idea why i cannot runt this script on my machine?

i am running winxp pro + sp2 (english), autoit 3.1.1

thx in advance