Question : unable to install Exchange SP2 Update Rollup 4

I have recently updated my Exchange 2007 server to SP2 but I am unable to install the post SP2 update rollup 4.  I have tried this on two Exchange servers but get the same error.  

Log Name:      Application
Source:        MsiInstaller
Date:          07/07/2010 11:30:58
Event ID:      1024
Task Category: None
Level:         Error
Keywords:      Classic
User:          mydomain\username
Computer:      exchangeserver.mydomain.com
Description:
Product: Microsoft Exchange Server - Update 'Update Rollup 4 for Exchange Server 2007 Service Pack 2 (KB981383) 8.2.254.0' could not be installed. Error code 1603. Windows Installer can create logs to help troubleshoot issues with installing software packages. Use the following link for instructions on turning on logging support: http://go.microsoft.com/fwlink/?LinkId=23127
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="MsiInstaller" />
    <EventID Qualifiers="0">1024</EventID>
    <Level>2</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2010-07-07T10:30:58.000Z" />
    <EventRecordID>5917450</EventRecordID>
    <Channel>Application</Channel>
    <Computer>exchangeserver.mydomain.com</Computer>
    <Security UserID="S-1-5... mysid...." />
  </System>
  <EventData>
    <Data>Microsoft Exchange Server</Data>
    <Data>Update Rollup 4 for Exchange Server 2007 Service Pack 2 (KB981383) 8.2.254.0</Data>
    <Data>1603</Data>
    <Data>(NULL)</Data>
    <Data>(NULL)</Data>
    <Data>
    </Data>
    <Data>
    </Data>
    <Binary>7B32344232433136342D444536362D343446452D423436382D4134364439443545364233317D207B44343241344142362D383942422D343730382D383738412D4639374136353034343645377D2031363033</Binary>
  </EventData>
</Event>

Answer : unable to install Exchange SP2 Update Rollup 4

Managed to track down the issue to the version of Powershell installed.  The Exchange post SP2 update rollups don't install with Powershell version 2.0 installed, I uninstalled Powershell 2.0 (which is listed as Windows update KB968930), installed the Exchange update rollup, then reinstalled Powershell from Windows Update.