Windows 95 Running a DOS App

I have an icon on the desktop that runs a DOS based Application. When I go into the App a menu appears, if I press the 1 or 2 or the number of the option I want to go into I may get a smiley face. Maybe some other graphical character. This may happen 2 or 3 times a day and then it might not happen for 2 or 3 weeks. I changed the Video card but with the same type of Video card (Trident chip set) I have another video card on order but something tells me it’s not the video card. Anyone have any clues????
Thanks
Gary