grinding from 1st to 2nd, 3rd to 2nd
 

I have noticed that my tranny grinds...makes a wierd grinding noise anyway....from first to second gear when I am going all out. Under normal driving conditions when I ease on to the throttle it is fine. It started only doing it when I was on the gas hard and letting the tranny shift for me. It did that for about 2 weeks and I went easy on it but now it is doing it more often. I am still easy on it but even when I take off fast and don't go WOT it still grinds sometimes. It does from 1st to 2nd when I take off. It does it from 3rd to 2nd when I am moving and punch the gas. It does not grind when I shift for myself at 4500 RPM's. Also when it grinds, my "servic engine soon" light comes on and my car starts running like crap. This could be because I am having problems with my fuel system but the tranny grinding sets off the fuel system problems more often now. I am worried, I wanna catch the problem before I have to get a whole new tranny. What is the problem and how much is it gonna cost?