"Chassis Intruded! Fatal Error. System Halted."

Hello everyone, bit of a head-scratcher here for you all- any help/ideas would be appreciated.

I recently (6 months ago) built a new rig. Main component of interest for this problem would be the MoBo, a Asus M4A78T-E.

It worked fine for the first few weeks. Nothing to complain about, until I started playing a rather graphics intensive game. Then I would experience random system lock-ups. (I attributed it to the game, not the GPU, as other games seemed fine).

Then about a month in something odd happened, I got system lock-ups doing non-gaming activities such as Internet Browsing or Word Processing. It didn't happen VERY often maybe once every 2 days. (I know that seems often, but I was overly tolerant.)

Then something else happened around the same time. Sometimes during boot-ups, after the Bios Splash screen I would get the error "Chassis Intruded! Fatal Error. System Halted." I could get around the error by simply restarting, and the system would work fine afterwards.

Recently, the problem has gotten much more persistent, happening sometimes multiple times a day. The Chassis Intrusion error always follows the system lock-up upon the first restart.

Things I have tried thus far:

Reset the CMOS.
Reseated the Chassis Intrusion Jumper Pin.
Tried booting up without the Chassis Intrusion Jumper Pin. (Won't Even Boot, gives a constant Chassis Intrusion Error.)

Any ideas?

Thanks.

Is there a setting in the bios for enable/disable chassis intrusion?
If so just disable it..

RMA it.The problem isn't about the Chasis Intrusions.It's about what happend before that, reguarding the random system lock ups.Just RMA the board.
Even if you bought the board 6 months ago it should still be under Warranty with Asus.