High pitched, scratchy sound?

My laptop is having problems with it's sound. Every time we try to watch video on youtube the sound is like a high pitched chime and its scratchy. i plugged in my headphones and it sounded the same(high pitched). I tried to see if it was just the web browser but it happened on both safari and internet explorer. I then played one of my pc games and the sound too was all messed up. Later i went on Oovoo and the sound was perfect and normal. Is there a way to fix the sound?