Screen Color

Anyone know why when I go into my computer/control panel/display/settings
And I go to change color settings ( because some games I tried to load ask for 256 colors)
all that is in there is 16 bit and 2 colors there is no 256 …I have two other computers and I never seen this …any clue as to why
Am running Win 98SE…I tried different video card and got the same thing…..