I was watching a video on youtube (using Chrome, OS is windows 7) when a pop up warned me that I had to calibrate my monitor again since the calibration was too old. This sounded strange, since I had done it yesterday, and I clicked it away to deal with it later. Then I locked the pc for some 30 minutes, and when I got back I found out some strange behaviour: facebook ssl certificate was expired, norton was disabled. I read with attention the error message of the ssl certificate and it was asking me if really today was may, 19th 2039. I fixed the date, restarted the computer and now everything seems fine.
What could have caused this leap forward by 26 years? I am updating my backup since it doesn't seem a good sign, but I would like to know if there is some diagnostics/check which I could try to understand what's going on.
Let me know if you need further details.
UPDATE: I add some further details, I was using a not-elevated account, with Chrome with the Adblock plugin. I use the Norton av and all the latest windows protection updated were installed, AFAIK.