Boot problem (fatal error... System halted)

Hello everyone,

I'm reaching out because I'm having a problem with my computer as follows:

When I start my computer, the motherboard image appears, then a single BEEP and a message appears: "Chassis intruded! Fatal error... System halted"



What can I do to solve the problem?

I have a temporary solution which is:
1. Turn off the PC
2. Remove the BIOS battery and put it back
3. Restart the PC
4. Choose the option "Load default BIOS settings"

But the problem is that every time my PC needs to restart or do something else, I have to repeat the operation.

My configuration: (everything was fine until now)

Operating System: Windows 7 64bit
Processor: Intel Core 2 Quad Q6700 2.67 GHz
Motherboard: ASUS P5QC (BIOS Rev 2.xx)
RAM: 4GB
Graphics Card: NVIDIA GEFORCE GTX 260

PS: I don't understand what's going on because I know how to play and everything, so it's a big BIOS problem or something I can't say.

Thank you in advance for your responses.