issue with pluging in power to hp zd7000 laptop / tvout on

I'am using a hp zd7000 laptop, and for years it was fine, but now when i plug in the laptop, with the tv out i get interference on the tv display, it not the tv out cables i tried many others, i even got a new cable for the power brick, the only way it goes away is if i use a 3 prong to two prong adapter, i also tried other outlets....what could be cause this?