If you have the iTunes Outlook addin in the COM Add-in section checked along with the NIS addin checked in Outlook 2003, during shutdown the will process will not unload. The Icon stays in the system tray and under the Task manager the process is still running. If you uncheck iTunes addin under Options, Other tab, Advanced options, Com add-ins then it works OK.
There seems to be a conflict that needs to be addressed by Symantec.