help with my screen

hello, im new here but i have a problem...My Macbook screen only opens about 90 degrees, after i open it more than half way it becomes completely dark (as if i turned the dimmer all the way down). Its not always at the EXACT point however. I had an appointment for the apple store and that day came around and it functioned near perfectly but some days i can't open it at all with out the screen dimming. Has anyone else had a problem similar to this? its about 2 years old but everything else functions perfectly, its just that the screen dims. Or does anyone know if this is covered under the warranty? i heard they don't cover the screen but i have a feeling that it is a wire that is connected to the screen, not the actual screen itself. Thanks!