Update Rollup 7 for Exchange Server 2007 Service Pack 1
Update Rollup 7 for Exchange Server 2007 Service Pack 1 (SP1) resolves issues that were found in Exchange Server 2007 SP1 since the software was released. This update rollup is highly recommended for all Exchange Server 2007 SP1 customers.
Get it here: http://www.microsoft.com/downloads/details.aspx?FamilyID=2074fefd-fa1a-4c3e-bf72-94585e454150
Description of RU 7: http://support.microsoft.com/kb/960384