I have a problem with getting certain keyboard input in both DInput for Win, and from DOS using an ISR. In both of my versions I have problems when the following 3 keys are being pressed at the same time: Left arrow, down arrow, and left ALT. (maybe just a vertical arrow and horizontal arrow with the ALT).
I've also seen this with many example keyboard ISRs I've downloaded. Is this a keyboard hardware problem, or is there some work-around for this. It seems that every game uses this combination, but except for an early version of DOOM I haven't noticed it other games.