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The date on my Windows 7 x64 PC has twice been set to the year 2028, which causes all sorts of stuff to stop working (website certs, TV guide listings, virus definition updates, etc). Any idea what would cause this?

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There are several solutions, that one of them will solve your problem for sure.

  • Sync your clock settings with (the previous answer shows you how to do that)

  • Check for any malicious software on your PC. Maybe it caused by some virus.

  • More likely solution: If nothing helps, you might need to replace your CMOS battery. It basically allows the motherboard to store data such as the time and power on settings. If the battery wears out, it'll need a replacement.

To replace the CMOS battery, you'll have to follow these steps (this was copied from some previous answer of mine, that I posted here in Super User):

  • This is the CMOS battery:

    alt text

  • As you can see, on the battery you'll see the model number (which in the picture is CR2032)

  • In the battery slot there is some metal clip that you have to press on it in order to pull off the battery. Take the battery off, and if your not sure what is the battery model, just take it with you to the nearest electronic shop, and they will know what to give you (it should cost less than 1$)

That's it. Just plug in the battery, and see if it solved your problem.

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But don't use your fingers to install it like that. Your fingers will leave a slight residue (i.e. a finger print) which can be enough to lower the lifetime of CMOS batteries. (So little power is used by the CMOS/RTC circuits that any other loss is significant.) – Richard Jul 15 '10 at 7:20
It's actually doesn't matter (from my actual experience). I've replaced many CMOS batteries like that from old computers (6 years old and even some older PC's) - and they work excellent till these days. – Matan Eldan Jul 15 '10 at 7:24
Replacing button batteries like this is never wise... – BloodPhilia Jul 15 '10 at 10:24
My knowledge in electricity is not that deep, but what i'm saying is that my actual experience (which I'm not ashame to say - is very deep) prove me otherwise than what you guys said. I've NEVER had any problems with CMOS batteries before and as I said - I've replaced ton's of them. In old PC's and New PC's as well. Sometimes, actual experience with stuff like this, is much better than any "voodoo" instructions. In real life the manual is not 100% clean of mistakes. – Matan Eldan Jul 15 '10 at 11:16

Some broken BIOS settings may cause it, but it's more likely it's a hidden software problem.

I would recommend to check the synchronize checkbox at the time settings page in WinXP, that will fix your clock by synchronizing with a NTP (Network Time) Server.

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