yup thats right its the CMOS battery inside. its getting weaker.
it keeps time, even when the computer is off. it also holds some other settings for BIOS but they should hold until the batter completely dies.
(its possible the above answer could help too, but I'm still thinking its the battery)
just open and replace.
they look like this http://www.jkg.in/wp-content/uploads/2006/06/cmos_battery.jpg
http://www.legitreviews.com/images/reviews/163/LRCorner.jpg
what kind of laptop do you have?
ah yes.
Dell Inspiron 1501
looks like this underneath?
http://farm1.static.flickr.com/176/440396406_a27122d895.jpg
hmmmm. this could be very hard.
this is what the motherboard looks like and the battery is the silver thing being held by the beige bracket.
http://www.laptopking.com/boards/959468.jpg
I'm not sure which compartment to open. I can't find any pages on how to do it so I'm trying to compare pictures I can find.
perhaps just try unscrewing each compartment underneath, one at a time and see if the battery is easy to get to through one of them.
techeon is correct. opening the whole thing is a VERY BIG PAIN and I myself would be hesitant to do so...... but removing covers for the compartments is not hard)
techeon_podcast
(it could very well be the battery. I've replaced two in my systems (not laptops) because of lost time (it fixed both) and they are constantly connected to the wall for power......... if your logic is correct, then they should NEVER loose time since they always have a power supply.)
quote from google.
"The CMOS battery in most Dell laptops last about two years. If the voltage on the battery drops below 3V, the machine will start losing time/date"
p.s. I turn off the automatic time syncing with servers after they changed the days we apply daylight savings time.... the servers would set my clock on the wrong days.
hmmmmmmmmmmmm. interesting
http://www.neowin.net/forum/index.php?showtopic=574882
http://www.computerhope.com/issues/ch000239.htm
"If your computer is losing its time or date settings, or you are receiving a message CMOS Read Error, CMOS checksum error, or CMOS Battery Failure, first attempt to leave the computer on for 24 hours. In some cases this can charge the battery and resolve your issue. This often resolves CMOS battery related issues when a computer has been left off for several months."