A restart from a previous installation is pending. Please restart the system and rerun setup.
Exchange Setup reads the following registry key to determine whether a system restart is required after installation or removal of a software update such as a security update, critical update, or hotfix.
Exchange Setup also checks the following registry key to determine whether a previous software update installation was not completed and the system must be restarted to finish the installation.
If setup still complains that a restart is needed after you've performed a restart, do the following:
•Set the HKLM\SOFTWARE\Microsoft\
•Delete the HKLM\SYSTEM\CurrentControlSet\