Unable to access any secure site

Hello. This morning I turned on my computer and curiously couldn't access some websites. I soon realized they were all https connections. For instance I can access http://amazon.com/, but I cannot access https://amazon.com/. The issue persists regardless of the browser I use. My e-mail client also cannot connect to certain accounts. The same goes for Windows Update.

I've searched this entire subforum for similar problems and haven't found anything that fixes the problem. I've flushed my DNS cache, reset windows sockets, synced time and date, checked whether any weird processes were running, and disabled my firewall (I don't use Windows Firewall or MSE).

Update: left the computer, made some oat bran, came back, and everything started working normally again. I don't know.

Oat bran is the solution.