GarageBand/Laptop Can't Multitrack?****************

So I tried recording using a USB mic and a direct input, using the 1/8 inch input on the computer in conjunction with my guitar. It worked for a couple of seconds but then after recording and having the monitor on for 15 seconds the sound of the instruments went to S*** and sounded like intense fuzz. Can laptops handle aggregate devices through the Audio Midi Setup? Why did it not work?

Thanks