Shortcut problem (southbridge burn)

Hi all,

My Southbridge chipset burn for the second time on my P4P800-E Deluxe.

The first the chipset burned only 1 hour after my first boot, so I think
that I've done something wrong or that I've a defect mobo.

But now, the computer work for 3 weeks. During this 3 weeks I don't have any
problems except one (that append two time, see below).

Here's the description of the problem. When I open or close the front door
of my Tsunami case (from thermaltake) the computer reboot and after I've a
warning that say:
- Chasis intrusion detected
- New processor installed
To resolve the problem, I entered in the BIOS, save setting and exit. After
that the computer work well. I repeat that this problem does't append every
time I open or close the door, but only two times in 3 weeks.

But last friday, I open the door and the computer close itself and just 3
seconds after that I smell that something burn inside so I unplug the
computer but it is too late.

So with this new info I think that the problem as something to do with the
case. There's two blue led on the front of the case and the HDD led, power
led, power switch and reset switch on the panel behind the front door.

My question is: Do you have an idea of what can cause that and how can I
check for the source of the problem (without burn a another mobo...)

Thanks a lot again for your help.

Note: Excuse my for my bad english, I hope you understand me.