sounds to me like you have a wore out headphone jack, possible with shortening of the contacts. you can try and use some compressed air and "gently" blow out the jack to see if there is any debris that could cause that. If not, the I would replace it. [http://www.youtube.com/watch?v=8iWU-x0ZpAw|Here are] some decent video instructions, and the part is available at many places [http://www.ipodrefresh.com/2nd-gen-ipod-touch-headphone-jack.html|like this.] Good Luck.