Thanks to Nathan for sending this in.
This patch resolves problems that were found in the Exchange 5.5 Web Client since SP4 was released. See "More Information" for a list of the fixes that are included in this patch.
This patch also includes a fix for the issue discussed in here. Visit that page for more information regarding that issue.
System Requirements
Exchange 5.5 SP4 already installed.
Operating System - Windows NT 4.0 & 2000