Wrong system time after switching off

Seems every time after power down and on again the next day, the system time and/or date are wrong. Noticed it first when Kaspersky software complained about being out of date right after updating.
This doesn’t seem to happen as long as the machine is left on. What could cause that? The machine is only a few months old.
Windows 7 Home Premium, SP1, 64-bit
Intel Core i3-2100 CPU, 3.1GHz, RAM 8G

Needs a CMOS battery.

Was also thinking that, but if the battery was dead, how could the machine power up and boot?

The system can boot without a working CMOS battery as long as power is going into the machine. This is especially true if the battery cannot hold a charge but is still in the machine. System design is modular - so if one component fails, you can still keep going. Some BIOS settings may even be retained as long as power is constantly going to the system. Use process of elimination and replace the CMOS battery first. It is the most cost effective fix. When the system is on you have power going to it and the system is not relying on the CMOS battery. The battery can maintain itself for years on newer system when it is not under prolonged use. Newer systems will not rely heavily on the battery if power is constantly going to the system, even when it is in the S5 state (motherboard LEDs stay on even in this state while the system is completely off). A big hint here is if you've had the system unplugged for a long period of time, it is almost certainly the battery. It is almost certainly the cause of your problem based on the information, and typically does happen. If it is a newer system, you may even have simply had a stroke of bad luck and the battery just went out. It does happen on occasion and is a very typical problem.

Just today, Monday 5-28, for the first time I'm aware of, the system time showed a Sunday 5-27 time. But the machine was running the whole night, not even restarted. So the wrong system time can't have been due to a bad CMOS battery. There must be another reason. Or can a bad battery also influence the time when the machine is on?

A faulty component, as simple as the battery, can cause a lot of trouble. The basic for the time / date is in the CMOS, and if that clicks-clacks, you may get the most weired dates and times. I've had it myself.

Not much more than a nickel for a battery. Try it!

Originally Posted by peri1224

Just today, Monday 5-28, for the first time I'm aware of, the system time showed a Sunday 5-27 time. But the machine was running the whole night, not even restarted. So the wrong system time can't have been due to a bad CMOS battery. There must be another reason. Or can a bad battery also influence the time when the machine is on?

If you don't power the laptop off, it will keep the time, in sleep mode the PC still keeps poewr to many components so that it can start right up.

Do you know if the bios time is the same as your system time? Do you have it set to update from the internet and you show the correct time zone?

Cmos battery was my first thought too. But this is a relatively new machine and a Cmos battery lasts 6 years on average. That, of course, does not mean that you battery is OK.

But I would rather look in the direction that Saltgrass has suggested.

that was, also, my 1st thought. Where the CMOS battery MAY be the issue, I would look @ the BIOS settings, too. If, that is not correct, neither will the 'desktop' time/date be correct or hold correctly. Consider both things.

Cheers,
Drew