The security certificate has expired -( by KenB )
This tutorial explains how to cope with the error message shown below:
If you are getting this error message when you try to connect to the internet or a specific website there could well be a simple solution.
It could be that your system is showing an incorrect Date or Time – or both.
You need to check the date and time that your machine is set to.
The time is shown in the bottom right corner.
If you need to adjust it right click on the icon > Adjust Date and Time
If you find that the date and time change again you probably need to change the CMOS battery on the motherboard.