Temporary loss of IE?

First, I'm running Vista on a two year old Sony laptop. Yesterday my computer began the day operating normally except for being a bit slow. After an hour or so I allowed it to hibernate for a few minutes while doing something else. When I started it up again, my task bar at the bottom had been altered and the icon for IE had disappeared. I went to the start menu and where IE is usually located at the top was the word "Internet". I clicked it but got an error message indicating that the program could not be found.

I then tried to locate the IE program file on the C drive but couldn't find it. Then I did a restart to re-boot but had the same problem when I re-started. I went to Restore Center and tried to restore to the last restore point. I kept getting an error message saying that I needed to insert the backup disc from 8/17/2008. I did as it said but still got the same error message.

Finally shut it down completely and then re-started it. It returned to the same situation as before. This time however, I tried to restore and everything worked just like its supposed to and all was back to normal.

Aside from snide comments about the reliability of Vista does anyone have any ideas as to why it happened? I run a continous anti-virus program and did a scan after I got things straightened out but no infection was found.