Know what we hate about updates like 931978? They basically stop all the Exchange services like the Information Store, SMTP service, WWW publishing service and fail to restart them. Basically, this means you have to reboot the server immediately so the services will restart. You can however, restart all the service manually from the Services MMC but until the server is rebooted the updates won't take effect. But you gotta remember to this immediately after the update has been installed.
It would be nice at the end of a Microsoft Update if it said something like ... we tried to restart these services but couldn't.... or ... the following services are stopped... This way you'd know from the update what wasn't working rather than from your customer who starts ringing after you have applied the update that Outlook is coming up with all these errors since Exchange server has stopped. Gotta admit we hate that, so come on Microsoft give us techies a little more information about exactly what your updates are doing in the background, especially what services are being stopped and started.