I have installed Windows 7 in a couple of computers and I have the same problem in all of them, it started with windows update not working, and the error pointed me to Microsoft article that says the problem is with date and time, but that wasn't the problem because I've checked everywhere, then i noticed that when i go to secure sites I always get the message "There is a problem with this website's security certificate", now these sites are well known sites, for example: https://login.yahoo.com
I used different Windows 7 version, some of the Windows edition used: Enterprise x64, Ultimate x32 and Ultimate x64 and all had the same problem. And I have been using Windows 7 Enterprise x64 edition in another location with no problems.
After a couple of failed attempts I checked my computer certificate: mmc > Add/Remove Snap-in > Certificates > Trusted Root Certification Authorities > Certificates, and I had the following Certificates (image is also available in the attachment):
So i went to Microsoft and downloaded:
"Update for Root Certificates [November 2009] (KB931125)"
And this solved this problem for me, now I can access any secure sites normally and use Windows Update and mesh normally.
But my question is why this is happening in the first place. I have been using Windows 7 since August and I've never faced this kind of problem, the only different variable is the environment, because this is the first time I am using Windows 7 in this environment, but I used Vista and XP before in this environment and never seen this problem.
Also there is a small different which I don't think it had any effect, but in the environment that has the problem all the computers are "HP Compaq dx7500 Microtower"
Also this is my certificates from my working computer.