If you've recently rolled out Outlook 2003 to some of your users, you may have experienced problems with the Outlook Web Access (OWA) 5.5 server hanging. Outlook 2003 adds new properties to the MAPI client and stores them in the Inbox, which causes heap corruption.
This heap corruption can cause OWA to hang when a user accesses the Inbox. The heap corruption can also hang programs that use Collaborative Data Objects (CDO) to access the mailbox.
If you're experiencing this problem, the good news is that Microsoft offers a hot fix, which you can download from Microsoft's Web site. Apply the hot fix to the OWA server, but only use the patch on servers that experience this specific problem. Before applying this hot fix, you must have Exchange 5.5 Service Pack 4 installed.
The hot fix, described in Microsoft Knowledge Base article 818709, corrects a heap corruption issue that causes OWA 5.5 to hang. However, this hot fix also overwrites files supplied by a patch released in Microsoft Security Bulletin MS03-047 with older files. This is a confusing issue, particularly because Microsoft released the hot fix after the security bulletin.
In a public newsgroup, we asked Microsoft support to help us straighten this out. A Microsoft support representative explained that while Microsoft issued MS03-047 before the hot fix, the files supplied in MS03-047 are newer and should contain the hot fix as well as the security patch.
Here's the bottom line: You should apply the MS03-047 patch to every OWA 5.5 site. If you've applied the MS03-047 security patch, the hot fix should be unnecessary. As always, it's a best practice to perform a full system backup and update your emergency repair or recovery disks prior to applying the hot fix.