loud feedback from comp when connected to MPC

Ok, heres the deals. Im interfacing Reason on my comp. I am running the sound output from comp to my MPC Analog input. now i find that when im connected and the power cable is connected to my laptop, i get this loud amount of feed back. BUT, when i disconnect the power plug the sound is crystal clear. I think i have a ground looping problem, but im not sure. Any help would be greatly apperciated yall
Thanks,
Spec-T

likewise

well. is there n e way to stop it?