Msgsrv32.exe
(Microsoft)
The Windows 32-bit Message Server. This essential program normally never appears in the Task List unless it has "hung"; it otherwise runs invisibly in the background performing a variety of essential services, a significant majority of which being to do with on-screen messages and notifications.
Recommendation :
As mentioned above this program only ever appears in the Task List if it has "hung". When that happens you will see "Not responding" next to it. Simply highlight it, and do an End Task on it (you may need to wait 5-10 seconds after the first "End Task" and re-do it). If MSGSRV32 hangs often, you will need to investigate.