The same thing I reported in my initial post in this thread happened just now. It's 21 Feb (10:15 AM CET, +1 GMT), I just turned on the computer and whatever updates were installed today left the 'Computer and Files' portion of Security Center unprotected. I simply clicked Fix and it was resolved.
Now, this isn't a big deal, but I doubt my wife would know where to look in the system tray to open Security Center. There's a glitch somewhere it would seem.
Just passing this on.
The next time this happens I'll look to see what modules have been turned off. Perhaps this can narrow down this issue.
SecurityCenter 9.3.127
VirusScan 13.3.115
PersonalFirewall 10.3.106
SiteAdvisor 2.9.242
AntiSpam 10.3.109
Parental Controls 11.3.103
Dave Horne