I have a Compaq Presario and the clock keeps resetting itself to 11pm in 2002 everytime i turn off the power at the mains. I have changed the CMOS battery and reset the time in the BIOS but it still keeps resetting. I now have no idea whats causing it.
did you replace the CMOS battery with a known working battery ?
usually you replace it with a standard CR2032
and how did you install the new battery ?
because if you installed it using uninsulated tweezers, you may have shorted the new battery out & you may also reset the BIOS / CMOS while you have the lid off
I replaced the battery with a new CR2032 battery.
It is easy to get at in my PC so i just changed it using my fingers so i doubt i could have shorted it. I changed the battery in the same way on a different PC and it worked as it should.