A week or so ago I noticed that Norton Internet Security (NIS) was occasionally crashing. What would happen was that the yellow icon in the system tray would disappear while I was busy with something else. When I noticed it was missing, I would try to restart it manually by clicking Start > Programs > Norton Internet Security > Norton Internet Security but this would always fail: sometimes I would get an error message, sometimes I would get a message suggesting that it thought I was a beta tester for NIS, but mostly the cursor would go busy for a few seconds and nothing would happen. Restarting the computer would clear the problem but it usually came back again after a few 10s of minutes or an hour or so.
My first thought was I had a virus which was sabotaging NIS. However, the problem seemed to have started following a LiveUpdate to NIS about a week or two ago. I remember this update because it was just after I had got back from a holiday and because it had required a system restart (which is unusual for NIS LiveUpdates). Following this update the version number of NIS was 188.8.131.52 (to see the version number go to the main NIS screen and click Help & Support > About). I looked in the system event log and it contained entries which seemed to be records of NIS crashing:
Event Type: Error
Source: Service Control Manager
Description: The Norton Internet Security service terminated unexpectedly. It has done this 1 time(s). The following corrective action will be taken in 120000 milliseconds: Restart the service.
I did a search on Google and came across this message on Norton community message board which pointed to an official patch for what seemed to be a very similar problem to the one I was experiencing. I downloaded the file KB20090821103237EN.exe, as indicated, and ran it. After restarting the computer NIS started correctly and I have had no problems since then. That was yesterday. The system has been running for at least 6 hours in total. It looks good.