Various Laptops with Power Issues

I have, over the past few years, have what seems to be the same issue with 4 different laptops.

About 3 years ago I had a Compaq Q60 laptop, one day I plugged the charger in and noticed there were no lights and it wasn't charging - the laptop continued to work till the battery went flat. After googling my issue it seemed like this was the norm for these laptops so I didn't bother fixing it. I decided to buy a new MacBook Pro 13". 14 months later I had the exact same thing happen as did with the Compaq. Once again after googling, I replaced the DC jack (see my first question in regards to this issue) but this didn't fix the issue. After months without a computer, a friend lent me his newish HP laptop, after a couple of months the SAME thing happened, I thought it may be the charger so I did nothing. About a month ago I then brought a used Macbook 13" (not a MacBook Pro) and placed my Pro harddrive into it and had a perfectly working mac, until last night SAME thing. Although I did notice that when I plugged the charger in the green light momentarily came on then went off and nothing since - is this all just a coincidence or what?

One thing was that I was using the same power outlet each time the laptops "died" but I have other electrical appliances (TV, DVD etc) using it too and they're fine. I'm at a total loss