E1505 keyboard issues.

I have an E1505 that's having some peculiar issues, that is only affecting the third and fourth row of keys. If I press the A key, it will also press the Z key. S also presses X. D and C. F and V. You get the jist of things. However, the dual key input also works the opposite way. If you hit Z, it'll press A. etc.

I went ahead and replaced the keyboard, figuring it was just a faulty keyboard. New keyboard did the same thing.

Updated the BIOS; same thing. It even does this in DOS. Completely out of Windows.

I'm wondering if this is a motherboard issue, or something I could fix easily. I really don't want to have to plunk down the money for a new one.

Any thoughts? All are appreciated.