Ex girlfriend keeps haunting me.

Please excuse the title, but she really is. My home computer once belonged to my ex girlfriend. I recently purchased my daughter an iPod touch for her birthday. I downloaded iTunes onto this computer and gave my daughter an Apple ID etc etc. However, her iPod won't sync with iTunes on the computer. Then, every now and then, it wants to sync iTunes with 'Kari's iPod'. Kari being the ex. I deleted iTunes from the computer, thinking that when I downloaded iTunes it merely updated the existing iTunes on the computer that I did not know was there. Now I can't even re download iTunes onto the computer.

Any thoughts on a possible solution?