Outlook 2000

I am encountering this issue with Outlook 2000 running on Win98SE. Everytime, my customer wants to close a read mail. It prompts that “an illegal operation has performed” and it will shutdown the entire Outlook. I have attempted to reconfigure a newprofile name following the instructions under MS KB 320856 but unsuccessful. Uninstall and re-install the Outlook2000 also does not work. If you click on “Details” it stated Outlook caused an invalid page fault in module Outllib.dll at .
Will appreciate any form of help