My computer suddenly thinks it is 8:33 am on 4/4/2004. It is pretty easy to switch it back, but I would prefer having the computer figure out the time and date itself. That I have not been able to figure out. How do I go about doing that?
What kind of computer? What operating system? Version?
If this happened after a reboot, it’s an almost certain sign that your CMOS battery has died. Good news: they’re relatively cheap and (usually) quite easy to replace.
And the operating system is …?
For example, if it were a Win7 system, clicking in the lower right-hand corner of the screen (where you should see the time and date) produces a popup box with a link that says, wait for it, … “Change date and time settings …”
On a Window machine, you may just be able to open the “Date and Time” dialog, click the “Internet Time” tab and select “Automatically synchronize with an Internet time server”. In the “Server” list you choose a time server like www.time.com. This is not available if you are in a domain.
This assumes and simplifies quite a bit. We would otherwise need to know more about your OS.
Meh. The battery may only be mostly dead.
I’m not trying to be snarky, I’m genuinely interested. Would a “mostly dead” battery reset the time to some random value? Why?
Yes, because the data is mostly there.
In my experience, a mostly-discharged CMOS battery can result in unpredictable internal timekeeping. I don’t pretend to understand the electronics, but I suspect it has to do with insufficient voltage. The CMOS batteries I’m familiar with are 3V watch-style batteries. If the clock they power is designed to run on 3V, I can only assume that there is a sliding scale of improper operation (read: incorrect timekeeping) down to 0V, at which it will cease to keep time at all and revert to it’s default time.
Note that the default time for the CMOS has nothing to do with the operating system’s reference time (which is what your link discussed), aside from network-connected operating systems that may be programmed to reset the CMOS clock to a server’s time: as I understand it, most PC operating systems simply ask the CMOS what time it is when they boot up and use that time.
Sorry for the incomplete information. It is a Dell Vostro, running Windows 7. I never even considered the battery since the computer is only 6 months old.
When I went to change time and date, and selected internet time it turns out it is already set to automatically synchronize with a government website. I am not sure if it happened after a reboot. I probably, but not definitely did.
Try this troubleshooting:
Set the time as indicated above.
Then turn the computer off for half an hour or so and boot it back up.
Check the time. If it’s more than a few seconds off, but not something identifiably “wrong but right” like off by a multiple of time zones, my first step would be to replace the battery.
If it’s off by a multiple of time zones, chances are somewhere it’s resetting itself to a time zone you don’t mean for it to. This would not, of course, explain why the date is wrong.
My money is still on the CMOS battery.
ETA: Saw your later post. It’s still worth trying the troubleshooting.
If it’s a laptop, be sure to remove the battery as well for the 30 minutes in KneadToKnow’s test.
Oh, sweet ziggity yes! I’m not up on all the Dell models, and if it’s not Inspiron, I don’t even think about the laptop option. 
For that matter: even if it’s a desktop, be certain and unplug it.
Yeah, when the battery on my old desktop died, the time would be OK as long as it was plugged in. Unplug it, and it would reset to 1980.