Norton disabled on startup

I turned on my computer after a couple of days, and these things occurred. 

1. No NIS System Tray Icon;

2. Nothing happened when I clicked on the NIS desktop shortcut (couldn’t open Norton at all);

3. Windows Firewall was turned on, instead of Norton Firewall (which has always been my default firewall.

I restarted my computer, and everything came back normally.  Can anyone tell me what caused this, and was my computer remotely taken over by someone/something?  Very nervous now…

I have NIS version 22.5.4.24