My front driver side wheel grinds into the break caliber ?

When in reverse my wheel rolls backwards but for some reason my rotor/axel ??? doesnt move thus the inside of the wheel grinds against my break caliber. My car is a 95 GSX eclipse and is AWD which is most liely why one wheel is messed up and not the other. Now, if I floor it and force the wheel to roll backwards once its like it locks in or something and is fine after that, very strange.... Just trying to get an idea of what might be wrong and what the repair cost would be. Thanks for your help.