Stuck in Charged Mode Constantly

A few months ago I started using an iPod dock. After a few weeks of using it I noticed my iPod was not turning off. When I turned it off the screen would go black then the ipod would show the screen that it shows when fully charged and connected to the computer. My computer doesn't recognize the iPod. The only device that recognizes it is the iPod dock. The battery is fine, because I just put a new battery in. I also know the battery is fine, because I can listen to it for hours. One weird thing is that sometimes after charging it on the dock it will fix itself. But when I have to charge it again, it goes back to being broke. I have searched everywhere for a solution and have not found one. I personally think there is something wrong with the firmware. I have tried re-setting through iTunes when it was working, but it still went back. Does anyone here have any solutions? Or is my iPod in an eternal loop.