I am getting electric shocks from the USB ports of my Laptop?

I have a Lenovo z580 laptop and since a few days, I am getting electric shocks whenever I touch the USB ports or the metal speaker grills. This happens only when the charger is plugged in, and doesn't happen all the time. While on charge, after a few hours of usage I get these shocks. I experienced this just now, I took out the charger plug from my laptop and tested it and found that some sort of current flow was there in it. But, this got solved when I unplugged the charger from the power socket and re-plugged it. Yesterday, I had my camera attached to my laptop and when I tried to pickup the camera, I got shocks from the metal part of the flash hotshoe in my camera. Can anyone tell me is this a problem of the charger or is it because of the power socket? And will this harm my laptop or any device connected to it, for example that camera?

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