I think this is a hardware issue and HP is sitting back and waiting for these laptops to get old and fade away. When mine was doing that, I connected my Power Pack from my dv7 to it (120 watt) it worked fine. I got a new 65 watt PP and now it works fine again.
I think the 65 watt Power Pack was maxing out charging it and when it gets old and possible looses some of its charging power it causes the problem.
I'm not an electrician but this solved the problem for me. None of the tricks posted here worked.