What does a gear with an exclamation point in the center of it mean on my dash?

I own a 1995 bmw 318is. I've always driven the car automatic but one day it became very sluggish. when the car is first turned on it drives normally. once it picks up speed it thrusts itself into gear. this is usually second gear. thats when the gear light comes on and its sluggish driving till its parked and engine off. one thing i did take note of was the fact that when turned off and then turned back on again the light would go away and the car would drive fine untill it was time to change gear. But while driving it manually i found that the car switched gears fine. that is only first, second and third. fourth seems to be out cause once i pass 45mph that light would come on and it was what i've described before all over again. the car will go over 45mph but with high rpms assuming that its stuck in third. i felt the need to elaborate and i hope i haven't confused anyone but i seriously need answers. thank you for your patience and assistance:)