What does this mean "CMOS Checksum Bad"

I'm getting this error sometimes, I wonder why ?

After this Everything loaded to default valves & i have to change everything again.

My motherboard's battery is low ?

My motherboard is ASUS P5K

Any help appreciated. Thanks

There are usually three main reasons that a CMOS Checksum Bad Error has occurred. They include:

1. CMOS Battery not functioning properly - Before starting enter BIOS and make note of the settings, it is possible that CMOS values will be lost, REPLACE the CMOS battery with a new one, just take all the information fron the old battery.

2. Your BIOS has been updated (either by you or possibly a virus) - IF you have updated the BIOS recently it is possible the values are corrupt, reset to default values or to the settings provided by the manufacturer. If you suspect a virus -scan, remove, and reset the values.

3. The computer was shut down improperly (i.e. shutting off the computer's power at the switch (Windows requires you to shut down your computer before shutting off the power), not usually a problem with XP but can still happen - Ensure you shut down the OS first.

Just on what the above poster said.

I have never, ever heard of number three. I'm not too sure how not shutting down XP would affect the CMOS/BIOS, as in nowhere in either the startup, shutdown, or general use (BIOS updating programs of course are the exception ;)) does the BIOS/CMOS get touched.

The other points are valid however, although number two will only happen once, next boot after you update the BIOS.

Thanks for the reply.

I haven't updated the BIOS & my motherboard is about 1 month old.

I think the reason is the 3. These days i've restarted few times.

Any more comments on this ?

Using Vista Home Premium 32bit