Outlook T&T: Resolving Forms Cache Corruption Problems in Outlook 2003

When my Microsoft Office Outlook 2003 users open an item in a public folder that uses a custom form, they see a message flash quickly on screen. Some also experience hangs, while others receive messages stating that the form isn't available and see the standard form, not the desired custom form. Do these problems have a solution?

Users of Outlook versions earlier than Outlook 2003 experience problems when the same custom form is in use in more than one location. The main symptom is that the local cache of custom forms becomes corrupted, causing users to receive an annoying message stating that the form can't be displayed.

In an effort to resolve this problem, Microsoft changed the way Outlook handled custom forms in Outlook 2003, locally caching each form instance separately. In other words, if the Organizational Forms library and three public folders' forms libraries each contained a copy of the same form, Outlook would cache four copies of the form on a user's local drive and, in theory, would determine which cached version to use according to the location of the item calling for the custom form.

This architectural change proved terrible in practice. Outlook 2003 was prone to hang if you opened more than five custom form items from a folder in the Public FoldersFavorites hierarchy. Microsoft issued a hotfix for that problem in January 2004, but the fix didn't eliminate all forms-cache problems. All too often, users still received the message that the form wasn't available and were frustrated by items opening in the standard form rather than a custom form.

Microsoft had a strong motivation for fixing this more general forms-cache corruption problem—it was affecting Microsoft's Business Contact Manager (BCM) add-in for Outlook 2003. BCM users had to manually clear the local forms cache often.

Office 2003 Service Pack 1 (SP1) is supposed to resolve these forms-cache corruption problems. I've seen some occasional forms-cache corruption symptoms with SP1 but far fewer than before.

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