I have a desktop Dell Inspiron 530 XP SP3 that was gaining time and dropping my internet connection often. It's about 10 years old, so I figured it was past time to change the CMOS battery and did so.
When I restarted, I attempted to synchronize with adjust date/time. It informed me that Windows could not synchronize for security reasons because my date did not match and to adjust the date and try again. Sure enough, I hadn't noticed but the date was reading 2007. So, I manually adjusted to both the correct date and correct time and tried again and got the same message. So then I went into BIOS setup. BIOS showed both the correct date and time.
This isn't a big issue at this point, I guess, because the time in both BIOS and on my desktop are showing the correct date and time and I no longer seem to be gaining time or dropping my internet connection since I replaced the battery, and I can manually adjust the date and time. However, it bothers me that I cannot seem to synchronize with an internet time server because it keeps saying that the date does not match. I have tried various time servers including pool.ntp.org. Any ideas would be very welcome.