HTTPS Not working on Macbook Pro

I'm having a weird issue on my Macbook Pro (OSX 10.7 Lion) where ANY site on ANY browser doesn't function if it is using HTTPS. For example, http://google.com will appear, but https://google.com will say 'Not Available'. It doesn't matter what browser I'm using (I've used Safari, Chrome and Firefox). I've encountered the issue on many different wifi networks.

I've tried adding a new 'Location' in my Network settings which didn't work. I've disabled the Mac Firewall, reset Wifi, disabled all Proxy checkboxes in the Wifi Settings. It's very strange and freaking me out a bit. Any help?

Solution 1:

Had this recently when my time and date was reset. Try setting them again.