"Chassis Intruded! Fatal Error. System Halted."

This is the second time I got this error now. I just shut it down, then reboot and it works fine after. What's the cause of this?

My mobo ASUS® P8P67 PRO (NEW REV 3.0): USB 3.0/SATA 6Gb/s, CrossFireX™ & SLI

Edit: It's done it again I think there maybe a problem.

Some motherboards have the option to disable chassis intruder alarm in bios settings,
but I would give tech support a call in case there is a problem with your motherboard.
call (0844 499 4000)
View waiting times http://www.pcspecialist.co.uk/call-waiting/

Did you get to the bottom of this?

ThankGod!!...Found a solution here:
http://www.techyv.com/questions/chassis-intruded-fatal-errorsystem-halted
Geez.Spent 3 hrs for this thing.:yawn:

The solution is already on this thread post 2.