BIOS problems (A8N-SLI)

[Vicioso]

Yesterday, when powering up my computer, the BIOS opened and this message showed:

Message Confirmation
The system intruded, chassis opened or tempered before,
please check the system.

I also noticed several BIOS settings were changed, for example: time and date among other settings. It seemed like it was reset.
After adjusting everything the computer/windows starts normaly. When turning off (a short time) and on nothing happens. But when turned off longer, I get the same issue.
The case wasn't moved, hit, kicked or opened.

Could this be a problem with the battery (motherboard)?
Help!

ACPI BIOS revision 1001
Asus A8n-sli
AMD S939 Athlon64 3500
Asus EN6600gt/td/128mb pci-e
3 GB RAM

[Gilly]

when you say turned off you mean with the power switch on the wall, or back of the PSU or unplugged completely from the wall?

the battery on the mainboard is used during the times i am talking about, and therefore if its flat then you may find the problem.

sometimes you find a jumper on the mainboard that stops this message, if it believes your case is open.

when my battery in the K8N Neo2 MSI board was flat it just said "Options have reset, press F1 to reconfigure" or words to that effect.

Hope that helps

[Vicioso]

When I turn the computer off leaving the powercable connected to the (wall) socket and turn it on, the computer starts up just fine. When I disconnect the powercable from the (wall) socket and turn it on (after a couple of minutes), I get this problem.

[Gilly]

yeah sounds like the battery, its very simple to replace the battery. iirc its a CR2025 in most motherboards, 3v lithium thingy

just check on it for sure, unplug PC, carefully plop the old one out and slap the new one it.

if that doesnt fix the problem ill be amazed

[Vicioso]

The message seems to be from the 'chassis intrusion connector'. I also turned this off in the BIOS.
I changed the battery and everything seems to be back to normal. Why does it not just mention the battery is empty instead of showing all kinds of different things...

Thank you for your help...

[Gilly]

no problem

i imgaine it might have a small capacitor in the circuit for the chassis detection system, and if thats flat the motherboard knows, so it flags up as being opened.

i honestly dont know though