HP offers the following advice in their Electrical Shock Safety article (specifically, the section on Preventing tingle current):
If you are experiencing a tingle current while using your HP notebook computer, use a 3-wire power cord with your AC adapter and make sure that it is plugged into a grounded (3-hole) power socket. Occasionally, the ground wiring is not well-connected to the earth ground, so the tingle current sensation may still occur even though a 3-wire cord is used. Also consider the following:
If you believe tingle current has caused a problem on your computer, here are a few tips:
Contact a qualified electrician for help with connecting the power cord's third wire to a metallic grounded structure, such as a plumbing pipe (if allowed by the local electrical code), if you often use the notebook from the same location.
Change the AC adapter.
Increase ground isolation by placing an anti-static chair mat on the floor below the chair that you typically sit in while using the notebook.
Use a different 2-wire power outlet (not a different outlet on the same circuit). Discontinue using a power strip or relocating to a different room may help.