Why is my laptop running so slow and making weird noises?

Ok so last week my laptop was making these weird noises like the sound of the music i was playing on itunes was in slow motion and had an echo and it sounded all robotic, weird i know. so i scanned my computer with my antivirus and deleted some tracking cookies and that pretty much fixed it, but today while i was listening to music it happens again and now my laptop is also running so slow, even if i type. what's wrong? is it a virus? i do have antivirus and my computer is only 3 months old. its an hp pavilion. how can i fix this?