Imagine my face when I got the following screen while logging into Gmail in the morning:

Chrome really suggested that www.google.com has no valid SSL certificate and may be dangerous.
Also services like Windows Live Messenger and Windows Update refused to work due to broken SSL certificates.

Turns out, I accidentally set the system clock after a bios reset to 28. July 2008 instead of 2009. I guess I looked at the system time about 3 times before noticing the error .

Funny: The wrong year also prevented me from syncing the time with time.windows.com to get to the right one.