Headphones crackling on right side?

Hi, i recently had to reinstall windows thanks to a bunch of trojans. After i did this everytime i plug headphones into the jack the right side is just a really loud crackling. I have tried several sets of headphones and the same thing happens. I know the headphone are all in working order becouse i have used them on this laptop before and all work fine in my MP3 player... Anyone know what could be the problem???