Error message when you try to install an Exchange service pack on a cluster node that is running Exchange Server 2003
Microsoft has published a KB about an error when we are installing Service Pack on a cluster node.
This problem occurs if the name of the default mailbox store includes a comma (,) or another special character. For example, this behavior occurs if the display name of the default mailbox store resembles the following display name:
Get it here: http://support.microsoft.com/default.aspx?scid=kb;en-us;926759&sd=rss&spid=1773