Application_ItemSend stopped working

Hi all,

I inherited an Outlook XP / Exchange 2003 environment with a
workstation where an ItemSend() script is active which removes all
attachments from internal forwarded messages. For some reason this
script stopt working suddenly. Only when I manually open the script-
editor (ALT + F11) to display the script and then close the script-
editor, the script works as expected. For the time being, I instructed
this user to open and close the script-editor every time Outlook
starts, but a more permanent solution is desired.

What can cause this sudden stop of this script?

TIA,
Wouter