I have seen several users have time changing or corruption issues but my problem adds another 'weird' happening to them.
My wife uses Windows 10 on a ThinkPad T420. Even after repeatedly setting the correct time (date, time-zone and time-server settings remain unchanged and set correctly) a few days later the displayed time always drops back 'exactly' two hours.
Here is some more appropriate information: My wife uses German Windows 10 (she is German and we live in Germany) and she has always had this time problem even some years ago when she was using German Windows XP Home Edition running in a dual-core desktop PC. I upgraded her machine to a Dell Inspiron laptop freshly installing her XP Home OS and moving all her data across to it. Exactly the same time problem appeared. The ThinkPad T420 is her latest hardware which came with Windows 7 and was upgraded to Windows 10. The same time problem remains.
Here is the next strange behaviour: I still have my old Windows XP Professional (English) on a four-core desktop PC. I also have Windows XP Professional (English) on an old Lenovo N3000 laptop. Neither have ever had any time changing problems. However, impressed with the wife's T420, I also bought one and it came with German Windows 7 which was also upgraded to Windows 10. This too has the same time changing problem.
I am a Linux user and on all of my hardware (therefore multi-OS) under Linux or Windows I have never had any time changing problems. It seems that if the Windows is a German problem then the time is puched back two hours.
I have checked all timer and time-server settings being the same used on my English Windows XP systems. I have followed an article regarding recommended Min-/Max- Pos-/Neg- offset settings in the registry for WTime32 config values. I discovered an article suggesting a BIOS update had repaired someone's dissimilar time problem. I have just applied an update for our T420s BIOS (ver. 1.46 raised to 1.48). Bear in mind the older XP hardware would have been completely different.
Has anyone any ideas as this is driving me nuts!