Hi guys,
I have a laptop that somehow the keyboard combination ctrl+alt+del on the built-in keyboard doesn't work anymore. When I say it doesn't work, I mean not just in Windows but also in DOS (booting from a bootable floppy diskette). However, ctrl+alt+del will work on an external keyboard (PS/2 or USB). I already replaced the built-in keyboard with a new one (thinking the old keyboard is bad) but it didn't fix it.
Is there anything else I can check/test before comdemming it's the motherboard that need to be replaced?

PS: except for the ctr+alt+del combination, all other keys seem to work OK on the built-in keyboard.