Input problem, help

i have some input problem with the keyborad in my game (not only in my game with other games also), when i combine these keys: Up Arrow key + Left Arrow Key + SpaceBar , the SpaceBar is not responding ( when i press spacebar the player need to give box). it also heppans with this combine: W + SpaceBar + Left Arrow, then the left arrow not responding. somebody know why?? (it also heppans in NBA2000 and all other games in my computer, its also happens on my freind computer).