Outlook and other applications taking ages to open or hanging? 

One of our machines received some automatic updates recently and immediately we noticed that it was running really badly. The browser was slow, file system access was sluggish and, most alarmingly, Outlook was taking several minutes to open. We watched all of the machine's processes using Process Explorer (a highly recommended replacement for Task Manager) and noticed that csc.exe, the C# command line compiler, was being opened by Outlook and was apparently causing it to take ages to start. A little bit of research suggested that a service needed by csc.exe might have stopped so we went through all the services and found that the COM+ System Application service was not running so we started it and set it to automatic, ran sfc/scannow at the command prompt for good measure and rebooted the machine. Outlook now opens in a matter of seconds and the machine is back up to full speed!