Problem with PC clock: keeps resetting itself to a date and time 17 days 14 hours 46 minutes ago. If I manually correct the clock, it stays correct for anything between a few seconds and 3 minutes and then resets itself. It always resets backwards by the same amount, not to a particular constant date (such as 1 January 2005). In other words, when the true date/time was 13:00 on 04/08/2016 (British Summer Time) it would reset to 22:14 on 17/07/2016, and when the true date/time was 18:10 on 04/08/2016 it would reset to 03:24 on 18/07/2016. The resetting happens only when the PC is switched on and connected to the internet. My time zone is ITC + 00:00 (UK) and I’m on Windows 7. Tried so far:
- If I power off the PC when it is showing the correct time and then turn it on again it still shows the correct time. It resets to the wrong time after an interval of anything between a few seconds and 3 minutes. That seems to eliminate the possibility of a dead CMOS battery.
- The error is not a whole number of hours (or half hours) away from correct the correct time. That seems to eliminate having slipped into the wrong time zone (and in any case would not explain the 17 days part of the error).
- My clock settings are set to synch on the net (once a week). If I go into control panel and click “Update now” when the clock is wrong, it is immediately corrected – but again resets itself to the wrong time after an interval of anything between a few seconds and 3 minutes. I have switched from time.windows.com to time.nist.gov and back again, and that makes no difference.
- Correct time is maintained when the PC is switched on if (a) the router is switched off or (b) the router is kept on but its telephone connection is unplugged. That seems to point to something external triggering a reset every few minutes.
UPDATE: The behaviour described above has lasted all day (past 9 hours+) and was absolutely consistent in the error introduced, but has just changed before I uploaded this question. For the past half hour it has been consistently subtracting just 12 hours (instead of 17 days 14 hours …) from the correct date and time. It is now showing 06:54 instead of 18:54. It still makes the change at some random interval up to 3 minutes after being corrected.
Any bright ideas?
UPDATE/POSTSCRIPT a week later. Without (knowingly) any input from me, the problem ceased, and has not recurred. The clock stopped resetting itself late that evening. Since then I have not replaced the battery, not re-set the time zone, or anything on the PC, nor done anything to the router. I remain completely mystified.
I have, however, today scoured through Windows System event logs, and this is what I found. The problem began, shortly after I logged on in the morning of 4 August, with this event (Kernel-General): "The system time has changed to 2016-07-17T16:35:43.949000000Z from 2016-08-04T07:20:30.407398600Z." The log reveals no clue what caused the change. Throughout that day, there were many similar logs, me correcting the date/time and something else shifting it back again. I have discovered that a similar log entry occurs during normal running, about every 10 minutes all day, throughout the time the PC is switched on. Usually the "change" is a fraction of a second; if it's the first of the day it may be a whole second. Except for 4 August, when I fought an invisible adversary who was determined to drag us 17+ days into the past!
Many thanks to all for your helpful ideas – even though, in the event, none seemed to provide the explanation/solution. If the problem recurs I’ll follow up GuitarPicker’s suggestion of diagnostic tools. Meanwhile, I thought it might be useful to provide this update, just in case anyone else has the same problem in future, or if anyone feels sufficiently intrigued or motivated to explore the mystery further.