Laptop shorts out charger?

I have a dell inspiron 8600 laptop and the charger I had for it went dead. (The green light went out), I moved it around a bit and the green light came on...then faded out. I continued fiddling around with it, the light came back on and I was able to get it to work for a few more hours without messing with it. When it became totally unresponsive, I threw it out and ordered a new one. The new charger came yesterday and when I plugged it into my laptop the screen had a bunch of horizontal white lines going across the screen. It looked like a TV with really bad reception and I wasn't able to use it until it had been charging a while I moved it around a bit and the white lines went away. Today the charger is exhibiting the same symptoms as that of the last charger. (The green light keeps fading out and it won't charge the laptop). Is it possible that I have a short somewhere in the laptop that is shorting out the charger? If so, how can I tell where it is? I have a pretty good knowledge of computers but I've never come across this before.