To correct this, please see the Microsoft's Knowledge Base article Q237924: PRB: ACL: Outlook 2000 Doesn't Properly Read ACL Settings
The resolution text found in this article is as follows:
On the computer where the permissions were to be set programmatically, run Microsoft Outlook 2000 and right-click on the Calendar folder. Choose Properties and select the Permissions tab to verify the access permissions for that folder. Do not make any changes to the permissions listed and click OK to close the dialog box.
You will now be able to access the Calendar folder with Outlook 2000 without an error.
Please contact Technical Support to create a Support Request for any issues you encounter that are not addressed by the User Guide, any Knowledge Base articles found on the website, or current Hotfixes or Service Packs available for download.