I just tested that again, on the Dell, and also on my IBM laptop. Both work fine, with completely different graphics (the laptop only has an integrated Intel card). Laptop tried with the red IBM mouse button and also with an USB mouse.
I'm afraid I really dont have a clue as to why you would be experiencing this problem, certainly this is the first report of anything like this with those buttons. And we would certainly have heard a
lot of such complaints if it were a regular one!
Do the buttons highlight when you hover the mouse over them, or are they completely dead?. If they dont highlight then there is a definate problem. (But why, as they use the same button code as say the "bombard" button that got you to that screen).
I presume you are not just trying an illegal direction pair (in which case no change would occur). I also presume you have tried pressing all the buttons at random to see if anything happens at all?.
Does this happen if you run the game in windowed mode as opposed to full screen?. Also - have you tried windowed mode with GDI graphics instead of DirectX?
As it happens on all your boxes - what is common between them all - as normally a weird like this would only happen on 1 "problem" box, in my experience. Any service task running in the background?.
Definately a weird one, let's see if we can get to the bottom of it!.
Cheers
Andy