Your security / anti virus may be trying to tell you that:
the security is turned off, expired, or malfunctioning, your fire wall may be turned off, or the computer may be infected.
check your security system, make sure it is updated, run a scan of the entire system, make sure the fire wall is turned on.
Click on the Red Exclamation button, it'll take to Windows Security Center, You can see what's the problem is.
Mostly of three types of problem only!
1.Automatic updates - May be turned off.(Turn it ON)
2.Antivirus program not installed/ not updated. (Solve by installing New Antivirus program or updating the existing one)
3.Windows Firewall is turned OFF (Turn it ON).
if you don't want to make any changes & also do not want that red exclamation mark, On LEFT BOTTOM of Security center, you can see an option.
Change Security Center notification settings (Something like that, I forgot), in that You can uncheck, as per your choice (But this is not recommended).
If you want a Security suite for your system, Download & Install the following 3 freewares & Keep them always updated. It forms a free complete security suite for your system!
1. Avira Anvivir - http://www.free-av.com/en/download/index.html .
Avira is best & light solution for excellent overall system protection & internet security with real time updates, .