Most sites list that you must press Shift-Keypad 0 to activate the cheat mode enabling code. On some versions, it will work without that. Another thing to consider is that NumLock is the pause key and if you press Keypad 0 while NumLock is off, it will register as Insert, which pastes the clipboard's content. Pressing Enter with the pasted text will crash the game if it is too long. Solution: make sure NumLock is ON before enabling cheat mode.