Microsoft has released Update Rollup 5 for Exchange Server 2007 Service Pack 1
>> Update Rollup 5 for Exchange Server 2007 Service Pack 1 (KB953467)
Update Rollup 5 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.
For a list of changes that are included in this update rollup, see KB953467.
>> Update Rollup 5 for Exchange Server 2007 Service Pack 1 (KB953467)